U.S. patent application number 16/723805 was filed with the patent office on 2020-06-25 for delivery systems and methods for left ventricular pacing.
The applicant listed for this patent is Medtronic, Inc.. Invention is credited to Ronald A. Drake, Nathan A. Grenz, Douglas S. Hine, Zhongping Yang.
Application Number | 20200197706 16/723805 |
Document ID | / |
Family ID | 69187965 |
Filed Date | 2020-06-25 |
![](/patent/app/20200197706/US20200197706A1-20200625-D00000.png)
![](/patent/app/20200197706/US20200197706A1-20200625-D00001.png)
![](/patent/app/20200197706/US20200197706A1-20200625-D00002.png)
![](/patent/app/20200197706/US20200197706A1-20200625-D00003.png)
![](/patent/app/20200197706/US20200197706A1-20200625-D00004.png)
![](/patent/app/20200197706/US20200197706A1-20200625-D00005.png)
![](/patent/app/20200197706/US20200197706A1-20200625-D00006.png)
![](/patent/app/20200197706/US20200197706A1-20200625-D00007.png)
![](/patent/app/20200197706/US20200197706A1-20200625-D00008.png)
![](/patent/app/20200197706/US20200197706A1-20200625-D00009.png)
![](/patent/app/20200197706/US20200197706A1-20200625-D00010.png)
View All Diagrams
United States Patent
Application |
20200197706 |
Kind Code |
A1 |
Grenz; Nathan A. ; et
al. |
June 25, 2020 |
DELIVERY SYSTEMS AND METHODS FOR LEFT VENTRICULAR PACING
Abstract
A method of delivering a pacing lead may include locating a
potential implantation site adjacent to or within the triangle of
Koch region of a patient's heart. The method may include advancing
a pacing lead to the potential implantation site. The pacing lead
has an elongate body and a fixation element coupled to a distal
portion and attachable to the right-atrial endocardium adjacent to
or within the triangle of Koch region. The method may include
implanting the pacing lead at the potential implantation site to or
sense electrical activity of the left ventricle in the basal and/or
septal region of the left ventricular myocardium of the patient's
heart. The pacing lead may include a lumen configured to receive a
guide wire. A sheath of a delivery system used to deliver the
pacing lead may include two or more curves to facilitate implanting
the pacing lead at the implantation site.
Inventors: |
Grenz; Nathan A.; (North
Oaks, MN) ; Drake; Ronald A.; (St. Louis Park,
MN) ; Yang; Zhongping; (Woodbury, MN) ; Hine;
Douglas S.; (Forest Lake, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Medtronic, Inc. |
Minneapolis |
MN |
US |
|
|
Family ID: |
69187965 |
Appl. No.: |
16/723805 |
Filed: |
December 20, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62783479 |
Dec 21, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 1/37512 20170801;
A61N 1/3682 20130101; A61B 5/04085 20130101; A61B 5/042 20130101;
A61B 5/1107 20130101; A61B 7/023 20130101; A61B 7/04 20130101; A61B
5/061 20130101; A61N 2001/0585 20130101; A61B 5/4836 20130101; A61B
2562/0204 20130101; A61N 1/3684 20130101; A61B 5/0031 20130101;
A61B 5/0538 20130101; A61B 5/6805 20130101; A61N 1/0573 20130101;
A61N 1/37518 20170801; A61N 1/3756 20130101; A61N 1/056 20130101;
A61N 1/3627 20130101; A61N 2001/0578 20130101 |
International
Class: |
A61N 1/368 20060101
A61N001/368; A61N 1/05 20060101 A61N001/05 |
Claims
1. A method of delivering a pacing lead comprising: locating a
potential implantation site adjacent to or within the triangle of
Koch region in the right atrium of a patient's heart; advancing a
pacing lead to the potential implantation site, the pacing lead
comprising an elongate body extending from a proximal portion to a
distal portion and a fixation element coupled to the distal portion
and attachable to the right-atrial endocardium adjacent to or
within the triangle of Koch region in the right atrium of the
patient's heart; and implanting the pacing lead at the potential
implantation site to deliver cardiac therapy to and sense
electrical activity of the left ventricle in the basal region,
septal region, or basal-septal region of the left ventricular
myocardium of the patient's heart.
2. The method according to claim 1, further comprising implanting a
left-ventricular electrode coupled to the distal portion of the
pacing lead from tissue adjacent to or within the triangle of Koch
region of the right atrium through the right-atrial endocardium and
optionally the central fibrous body to deliver cardiac therapy to
and sense electrical activity of the left ventricle in the basal
region, septal region, or basal-septal region of the left
ventricular myocardium of the patient's heart.
3. The method according to claim 1, further comprising positioning
an atrial electrode of the pacing lead adjacent to or proximal to
the fixation element to deliver cardiac therapy to or sense
electrical activity of the atrium of the patient's heart.
4. The method according to claim 1, wherein locating the potential
implantation site comprises: optionally inserting a guide wire into
a lumen of a sheath; advancing the guide wire and the sheath into
the coronary sinus of the patient's heart; advancing a
needle-tipped dilator over the guide wire and through the lumen of
the sheath to the coronary sinus; engaging tissue in the potential
implantation site adjacent to or within the triangle of Koch region
in the right atrium of the patient's heart with the needle-tipped
dilator; testing the potential implantation site adjacent to or
within the triangle of Koch region in the right atrium of the
patient's heart using the needle-tipped dilator; and determining
whether the potential implantation site is acceptable based on the
testing using the needle-tipped dilator.
5. The method according to claim 4, further comprising: withdrawing
the needle-tipped dilator from tissue in the potential implantation
site in response to determining that the potential implantation
site is not acceptable; and optionally locating a new potential
implantation site adjacent to or within the triangle of Koch region
in the right atrium of the patient's heart.
6. The method according to claim 4, further comprising forming an
opening in tissue in the potential implantation site using the
needle-tipped dilator in response to determining that the potential
implantation site is acceptable.
7. The method according to claim 1, further comprising preparing
the potential implantation site for the pacing lead based on a size
of a guide wire.
8. The method according to claim 7, wherein preparing the potential
implantation site for the pacing lead comprises: advancing the
guide wire to the potential implantation site; advancing a sheath
over the guide wire and into an opening in tissue in the potential
implantation site formed by a needle-tipped dilator; and
withdrawing the needle-tipped dilator and the guide wire through a
lumen of the sheath, wherein the pacing lead is advanced to the
potential implantation site while the pacing lead is at least
partially disposed in the lumen of the sheath.
9. The method according to claim 7, wherein preparing the potential
implantation site for the pacing lead comprises: advancing the
guide wire into an opening in tissue in the potential implantation
site formed by a needle-tipped dilator; withdrawing the
needle-tipped dilator over the guide wire; and exchanging the
needle-tipped dilator with the pacing lead, wherein the pacing lead
is advanced to the potential implantation site over the guide
wire.
10. The method according to claim 4, wherein the needle-tipped
dilator comprises a dilator portion and a needle portion separable
from the dilator portion.
11. The method according to claim 1, further comprising: testing
the potential implantation site using the pacing lead; determining
whether the potential implantation site is acceptable based on the
testing using the pacing lead; and fixing the pacing lead in the
potential implantation site in response to determining that the
potential implantation site is acceptable based on the testing
using the pacing lead.
12. A pacing lead delivery system comprising: a sheath comprising
an elongate body defining a lumen extending between a proximal
portion and a distal portion; a guide wire at least partially
disposable in the lumen of the sheath; a needle-tipped dilator
configured to advance over the guide wire and to engage tissue in a
potential implantation site; and a pacing lead comprising an
elongate body extending from a proximal portion to a distal portion
and a fixation element coupled to the distal portion and attachable
to an implantation site in the right-atrial endocardium adjacent to
or within the triangle of Koch region in the right atrium of a
patient's heart to deliver cardiac therapy to and sense electrical
activity of the left ventricle in the basal region, septal region,
or basal-septal region of the left ventricular myocardium of the
patient's heart.
13. The pacing lead delivery system according to claim 12, wherein
the elongate body defines a lumen extending between the proximal
portion and the distal portion configured to receive the guide
wire.
14. The pacing lead delivery system according to claim 12, wherein
the fixation element of the pacing lead comprises a helical
attachment element.
15. The pacing lead delivery system according to claim 14, wherein
the pacing lead is freely rotatable relative to the sheath, the
guide wire, or both.
16. The pacing lead delivery system according to claim 12, wherein
the sheath comprises a fixed curve configured to extend to the
implantation site adjacent to or within the triangle of Koch region
in the right atrium of the patient's heart using the coronary
sinus.
17. The pacing lead delivery system according to claim 12, wherein
the sheath is deflectable and comprises a first curve segment and a
second curve segment distal to the first curve segment configured
to extend to the implantation site adjacent to or within the
triangle of Koch region in the right atrium of the patient's heart
through the coronary sinus.
18. The pacing lead delivery system according to claim 17, wherein
the first curve segment has a first radius of curvature and the
second curve segment has a second radius of curvature less than the
first radius of curvature.
19. The pacing lead delivery system according to claim 17, wherein
the first curve segment is aligned to a first plane and the second
curve segment is aligned to a second plane having a different
orientation than the first plane.
20. The pacing lead delivery system according to claim 17, wherein
the first curve segment is adjustable relative to the second curve
segment.
21. The pacing lead delivery system according to claim 12, wherein
the needle-tipped dilator or guide wire is configured to form an
opening in tissue in the potential implantation site.
22. The pacing lead delivery system according to claim 21, wherein
the sheath is configured to be inserted into the opening in tissue
formed by the needle-tipped dilator to guide the pacing lead to the
potential implantation site.
23. The pacing lead delivery system according to claim 21, wherein
the guide wire is configured to be inserted into the opening in
tissue formed by the needle-tipped dilator to guide advancement of
the pacing lead to the potential implantation site.
24. A pacing lead delivery system comprising: a sheath comprising
an elongate body defining a lumen extending between a proximal
portion and a distal portion; a guide wire at least partially
disposable in the lumen of the sheath and configured to engage
tissue in a potential implantation site; and a pacing lead
comprising an elongate body extending from a proximal portion to a
distal portion and a fixation element coupled to the distal portion
and attachable to an implantation site in the right-atrial
endocardium adjacent to or within the triangle of Koch region in
the right atrium of a patient's heart to and sense electrical
activity of the left ventricle in the basal region, septal region,
or basal-septal region of the left ventricular myocardium of the
patient's heart.
25. The pacing lead delivery system of claim 24, wherein the
elongate body defines a lumen extending between the proximal
portion and the distal portion configured to receive the guide
wire.
Description
[0001] The present application claims the benefit of U.S.
Provisional Application Ser. No. 62/783,479, filed Dec. 21, 2018,
which is incorporated by reference in its entirety.
[0002] The present technology is generally related to medical
device methods and systems, such as methods and systems for
implantable medical device implantation and use.
[0003] The cardiac conduction system includes the sinus atrial (SA)
node, the atrioventricular (AV) node, the bundle of His, bundle
branches and Purkinje fibers. A heartbeat is initiated in the SA
node, which may be described as the natural "pacemaker" of the
heart. An electrical impulse arising from the SA node causes the
atrial myocardium to contract. The electrical impulse, or
electrical pulse or signal, is conducted to the ventricles via the
AV node which inherently delays the conduction to allow the atria
to stop contracting before the ventricles begin contracting thereby
providing proper AV synchrony. The electrical impulse is conducted
from the AV node to the ventricular myocardium via the bundle of
His, bundle branches, and Purkinje fibers.
[0004] Patients with a conduction system abnormality, such as poor
AV node conduction or poor SA node function, may receive an
implantable medical device (IMD), such as a pacemaker, to restore a
more normal heart rhythm and AV synchrony. Some types of IMDs, such
as cardiac pacemakers, implantable cardioverter defibrillators
(ICDs), or cardiac resynchronization therapy (CRT) devices, provide
therapeutic electrical stimulation to a heart of a patient via
electrodes on one or more implantable endocardial, epicardial, or
coronary venous leads that are positioned in or adjacent to the
heart. The therapeutic electrical stimulation may be delivered to
the heart in the form of pulses or shocks for pacing,
cardioversion, or defibrillation. In some cases, an IMD may sense
intrinsic depolarizations of the heart, and control the delivery of
therapeutic stimulation to the heart based on the sensing.
[0005] Delivery of therapeutic electrical stimulation to the heart
can be useful in addressing cardiac conditions such as ventricular
dyssynchrony that may occur in patients. Ventricular dyssynchrony
may be described as a lack of synchrony or a difference in the
timing of contractions in the right and left ventricles of the
heart. Significant differences in the timing of contractions can
reduce cardiac efficiency. CRT, delivered by an IMD to the heart,
may enhance cardiac output by resynchronizing the electromechanical
activity of the ventricles of the heart. CRT may include
"triple-chamber pacing" when pacing the right atrium, right
ventricle, and left ventricle.
[0006] Cardiac arrhythmias may be treated by delivering electrical
shock therapy for cardioverting or defibrillating the heart in
addition to cardiac pacing, for example, from an ICD, which may
sense a patient's heart rhythm and classify the rhythm according to
an arrhythmia detection scheme in order to detect episodes of
tachycardia or fibrillation. Arrhythmias detected may include
ventricular tachycardia (VT), fast ventricular tachycardia (FVT),
ventricular fibrillation (VF), atrial tachycardia (AT) and atrial
fibrillation (AT). Anti-tachycardia pacing (ATP) can be used to
treat ventricular tachycardia (VT) to terminate substantially many
monomorphic fast rhythms.
[0007] Dual chamber medical devices are available that include a
transvenous atrial lead carrying electrodes that may be placed in
the right atrium and a transvenous ventricular lead carrying
electrodes that may be placed in the right ventricle via the right
atrium. The dual chamber medical device itself is generally
implanted in a subcutaneous pocket, and the transvenous leads are
tunneled to the subcutaneous pocket. A dual chamber medical device
may sense atrial electrical signals and ventricular electrical
signals and can provide both atrial pacing and ventricular pacing
as needed to promote a normal heart rhythm and AV synchrony. Some
dual chamber medical devices can treat both atrial and ventricular
arrhythmias.
[0008] Intracardiac medical devices, such as a leadless pacemaker,
have been introduced or proposed for implantation entirely within a
patient's heart, eliminating the need for transvenous leads. A
leadless pacemaker may include one or more electrodes on its outer
housing to deliver therapeutic electrical signals and/or sense
intrinsic depolarizations of the heart. Intracardiac medical
devices may provide cardiac therapy functionality, such as sensing
and pacing, within a single-chamber of the patient's heart.
Single-chamber intracardiac devices may also treat either atrial or
ventricular arrhythmias or fibrillation. Some leadless pacemakers
are not intracardiac and may be positioned outside of the heart
and, in some examples, may be anchored to a wall of the heart via a
fixation mechanism.
[0009] In some patients, single-chamber devices may adequately
address the patient's needs. In other patients, single-chamber
sensing and therapy may not fully address cardiac conduction
disease or abnormalities in all patients, for example, those with
some forms of AV dyssynchrony or tachycardia. Dual chamber sensing
and/or pacing functions, in addition to ICD functionality in some
cases, may be used to restore more normal heart rhythms.
SUMMARY
[0010] The techniques of this disclosure generally relate to
methods and systems for delivering an implantable medical device
for left ventricular pacing, for example, to an implantation site
adjacent to or within the triangle of Koch region of a patient's
heart. In some embodiments, the implantation site may be accessed
using the coronary sinus system of the patient's heart. A delivery
system may include a sheath having two or more curves to facilitate
delivering a pacing lead to an implantation site. The pacing lead
may include a lumen, which may be appropriately sized to receive a
guidewire. The pacing lead may also include a fixation element to
attach to cardiac tissue. In particular, the pacing lead may be
configured to attach to an implantation site in the right-atrial
endocardium adjacent to or within the triangle of Koch region in
the right atrium of the patient's heart.
[0011] In one aspect, the present disclosure provides a method of
delivering a pacing lead including: locating a potential
implantation site adjacent to or within the triangle of Koch region
in the right atrium of a patient's heart. The method also includes
advancing a pacing lead to the potential implantation site. The
pacing lead includes an elongate body extending from a proximal
portion to a distal portion and a fixation element coupled to the
distal portion and attachable to the right-atrial endocardium
adjacent to or within the triangle of Koch region in the right
atrium of the patient's heart. The method also includes implanting
the pacing lead at the potential implantation site to deliver
cardiac therapy to or sense electrical activity of the left
ventricle in the basal region, septal region, or basal-septal
region of the left ventricular myocardium of the patient's
heart.
[0012] In another aspect, the present disclosure provides a pacing
lead delivery system including: a sheath having an elongate body
defining a lumen extending between a proximal portion and a distal
portion; a guide wire at least partially disposable in the lumen of
the sheath; a needle-tipped dilator configured to advance over the
guide wire and to engage tissue in a potential implantation site;
and a pacing lead having an elongate body extending from a proximal
portion to a distal portion and a fixation element coupled to the
distal portion and attachable to an implantation site in the
right-atrial endocardium adjacent to or within the triangle of Koch
region in the right atrium of a patient's heart to deliver cardiac
therapy to or sense electrical activity of the left ventricle in
the basal region, septal region, or basal-septal region of the left
ventricular myocardium of the patient's heart.
[0013] In another aspect, the present disclosure provides, a pacing
lead including an elongate body defining a lumen extending from a
proximal portion to a distal portion configured to receive a guide
wire; and a left-ventricular electrode coupled to the elongate body
implantable from tissue adjacent to or within the triangle of Koch
region of the right atrium through the right-atrial endocardium to
deliver cardiac therapy to or sense electrical activity of the left
ventricle in the basal region, septal region, or basal-septal
region of the left ventricular myocardium of a patient's heart.
[0014] In another aspect, the present disclosure provides a pacing
lead delivery system including a sheath having an elongate body
defining a lumen extending between a proximal portion and a distal
portion; a guide wire at least partially disposable in the lumen of
the sheath and configured to engage tissue in a potential
implantation site; and a pacing lead having an elongate body
extending from a proximal portion to a distal portion and a
fixation element coupled to the distal portion and attachable to an
implantation site in the right-atrial endocardium adjacent to or
within the triangle of Koch region in the right atrium of a
patient's heart to or sense electrical activity of the left
ventricle in the basal region, septal region, or basal-septal
region of the left ventricular myocardium of the patient's
heart.
[0015] The details of one or more aspects of the disclosure are set
forth in the accompanying drawings and the description below. Other
features, objects, and advantages of the techniques described in
this disclosure will be apparent from the description and drawings,
and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a conceptual diagram of an illustrative cardiac
therapy system including an intracardiac medical device implanted
in a patient's heart and a separate medical device positioned
outside of the patient's heart for use with, e.g., the illustrative
methods of FIGS. 29-34.
[0017] FIGS. 2-4 are conceptual diagrams of illustrative cardiac
therapy systems including medical devices including leads with
electrodes implanted in a patient's heart for use with, e.g., the
illustrative methods of FIGS. 29-34.
[0018] FIG. 5 is an enlarged conceptual diagram of the intracardiac
medical device of FIG. 1 and anatomical structures of the patient's
heart.
[0019] FIG. 6 is a conceptual diagram of a map of a patient's heart
in a standard 17 segment view of the left ventricle showing various
electrode implantation locations for use with, e.g., the
illustrative systems and devices of FIGS. 1-4 and FIGS. 16-28.
[0020] FIG. 7 is a perspective view of an intracardiac medical
device having a distal fixation and electrode assembly that
includes a distal housing-based electrode implemented as a ring
electrode for use with, e.g., the illustrative systems and devices
of FIGS. 1-4 and FIGS. 16-28.
[0021] FIG. 8 is a block diagram of illustrative circuitry that may
be enclosed within the housing of the medical devices of FIGS. 1-4
and FIGS. 16-28, for example, to provide the functionality and
therapy described herein.
[0022] FIG. 9 is a perspective view of another illustrative
intracardiac medical device for use with, e.g., the illustrative
systems and devices of FIGS. 1-4 and FIGS. 16-28.
[0023] FIG. 10 is a flowchart of an illustrative method of
detecting atrial activity using an atrial motion detector for use
with, e.g., the illustrative systems and devices of FIGS. 1-4 and
FIGS. 16-28.
[0024] FIG. 11 is a flowchart of an illustrative method of
detecting heart sounds to represent physiological response
information for use with, e.g., the illustrative systems and
devices of FIGS. 1-4 and FIGS. 16-28.
[0025] FIG. 12 is a flowchart of an illustrative method of
detecting bioimpedance to represent physiological response
information for use with, e.g., the illustrative systems and
devices of FIGS. 1-4 and FIGS. 16-28.
[0026] FIG. 13 is a diagram of an illustrative system including
electrode apparatus, display apparatus, and computing apparatus for
use with, e.g., the illustrative systems and devices of FIGS. 1-4
and FIGS. 16-28.
[0027] FIGS. 14-15 are diagrams of illustrative external electrode
apparatus for measuring torso-surface potentials for use with,
e.g., the illustrative systems and devices of FIGS. 1-4 and FIGS.
16-28.
[0028] FIGS. 16-25 are illustrations showing various configurations
of a pacing lead delivery system for use with, e.g., the
illustrative systems and devices of FIGS. 1-4 and methods of FIGS.
29-34.
[0029] FIG. 26 is an illustration of a right anterior oblique
cutaway view of the patient's heart and the illustrative pacing
lead delivery system of FIGS. 16-25.
[0030] FIG. 27 is an illustration of an overhead cutaway view the
patient's heart and the illustrative pacing lead delivery system of
FIGS. 16-25 in the same position as shown in FIG. 26.
[0031] FIG. 28 is an illustration of the patient's heart showing a
target implantation zone for use with, e.g., the illustrative
systems and devices of FIGS. 1-4 and the illustrative pacing lead
delivery system of FIGS. 16-25.
[0032] FIG. 29 is a flow diagram of a method of using, e.g., the
illustrative systems and devices of FIGS. 1-4 and the illustrative
pacing lead delivery system of FIGS. 16-28.
[0033] FIG. 30 is a flow diagram of one example of a method for
locating a potential implantation site for use with, e.g., the
illustrative method of FIG. 29.
[0034] FIG. 31 is a flow diagram of a further example of a method
for locating a potential implantation site for use with, e.g., the
illustrative method of FIG. 29.
[0035] FIG. 32 is a flow diagram of one example of a method for
preparing an implantation site for use with, e.g., the illustrative
method of FIG. 29.
[0036] FIG. 33 is a flow diagram of another example of a method for
preparing an implantation site for use with, e.g., the illustrative
method of FIG. 29.
[0037] FIG. 34 is a flow diagram of a further example of a method
for preparing an implantation site for use with, e.g., the
illustrative method of FIG. 29.
DETAILED DESCRIPTION
[0038] The techniques of this disclosure generally relate to
delivering implantable medical devices to provide cardiac therapy
using the cardiac conduction system or left ventricular myocardium.
In particular, the delivery systems and techniques may be used to
implant implantable medical devices through the right atrium to the
left ventricle (e.g., ventricle-from-atrium, or VfA) from the
triangle of Koch region or the coronary sinus. In some embodiments,
various techniques described herein may be applied to His bundle or
bundle branch pacing applications that use the cardiac conduction
system. Various non-limiting examples of cardiac therapy include
single chamber or multiple chamber pacing (e.g., dual or triple
chamber pacing), atrioventricular synchronous pacing, asynchronous
pacing, triggered pacing, cardiac resynchronization pacing, or
tachycardia-related therapy. Although reference is made herein to
implantable medical devices, such as a pacemaker or ICD, the
methods and processes may be used with any medical devices,
systems, or methods related to a patient's heart. Various other
applications will become apparent to one of skill in the art having
the benefit of the present disclosure.
[0039] It may be beneficial to provide an implantable medical
device delivery system and technique to locate an electrode for
sensing or pacing the left ventricular myocardium or the cardiac
conduction system. It may also be beneficial to provide a delivery
system and technique to deliver an implantable medical device
adjacent to or within the triangle of Koch region at an appropriate
angle for left ventricular pacing, for example, using the
endocardium and/or the cardiac conduction system.
[0040] As used herein, the term "capture" generally refers to
obtaining information or data, for example, related to imaging. The
term "capture" in the context of pacing (e.g., effective capture of
the heart from pacing) refers to determining whether a desired
response is sensed in response to stimuli, such as sensing
desirable electrical activity in response to electrical pulses
delivered to a portion of the heart.
[0041] As used herein, the term "effective" generally refers to
meeting conditions that would be sufficient to a person of ordinary
skill in the art for performing a particular function. For example,
effective pacing of the left ventricle may result in capture of the
left ventricle when electrical or mechanical activity of the left
ventricle is sensed and determined to provide cardiac therapy as
desired.
[0042] The present disclosure provides a technique for delivering
an implantable medical device for left ventricular pacing, for
example, to an implantation site adjacent to or within the triangle
of Koch region of a patient's heart. In some embodiments, the
implantation site may be accessed using the coronary sinus system
of the patient's heart. In particular, the delivery systems and
techniques may be used to deliver a pacing lead to an implantation
site. Delivery systems may include a sheath having two or more
curves to facilitate delivering the pacing lead to an implantation
site. The pacing lead may include a lumen, which may be
appropriately sized to receive a guidewire. The pacing lead may
also include a fixation element to attach to cardiac tissue. In
particular, the pacing lead may be configured to attach to an
implantation site in the right-atrial endocardium adjacent to or
within the triangle of Koch region in the right atrium of the
patient's heart.
[0043] In some embodiments, the tissue-piercing electrode may be
implanted in the basal region, septal region, or basal-septal
region of the left ventricular myocardium of the patient's heart
from the triangle of Koch region of the right atrium through the
right-atrial endocardium and central fibrous body. In a leadless
implantable medical device, the tissue-piercing electrode may
leadlessly extend from a distal end region of a housing of the
device, and the right-atrial electrode may be leadlessly coupled to
the housing (e.g., part of or positioned on the exterior of the
housing). The right-atrial motion detector may be within the
implantable medical device. In a leaded implantable medical device,
one or more of the electrodes may be coupled to the housing using
an implantable lead. When the device is implanted, the electrodes
may be used to sense electrical activity in one or more atria
and/or ventricles of a patient's heart. The motion detector may be
used to sense mechanical activity in one or more atria and/or
ventricles of the patient's heart. In particular, the activity of
the right atrium and the left ventricle may be monitored and,
optionally, the activity of the right ventricle may be monitored.
The electrodes may be used to deliver cardiac therapy, such as
single-chamber pacing for atrial fibrillation, atrioventricular
synchronous pacing for bradycardia, asynchronous pacing, triggered
pacing, cardiac resynchronization pacing for ventricular
dyssynchrony, anti-tachycardia pacing, or shock therapy. Shock
therapy may be initiated by the implantable medical device. A
separate medical device, such as an extravascular ICD, which may
also be implanted, may be in operative communication with the
implantable medical device and may deliver an electrical shock in
response to a trigger, such as a signaling pulse (e.g., triggering,
signaling, or distinctive electrical pulse) provided by the
device.
[0044] In general, electrical or mechanical activity may be sensed,
determined, acquired, or monitored using various techniques
available to one having ordinary skill in the art who has the
benefit of the present disclosure. As used herein, the term
"monitoring" generally refers to sensing, acquiring, or receiving
data or information that may be used, for example, being processed
or stored.
[0045] The present disclosure also provides a technique to deliver
and implant a medical device, for example, in the triangle of Koch
region in the right atrium. Various devices may be used to identify
the general location of the triangle of Koch region, which may be
described as an implantation site. A flexible lead, or another
probe, may be advanced to the potential implantation site and used
to identify a precise location for implantation of a medical
device, such as an electrode, leadlet, lead, or intracardiac
device. In particular, the techniques of the present disclosure may
be used to implant a device to provide synchronous pacing to
patients with dyssynchrony, as well as provide dual chamber pacing
for bradycardia patients with moderate heart failure.
[0046] FIGS. 1-4 show examples of various cardiac therapy systems
that may be implanted using, for example, the methods shown in
FIGS. 29-34 to deliver a medical device to an implantation site. In
these views, the left ventricle (LV) is positioned generally behind
the right ventricle (RV).
[0047] Although the present disclosure describes leadless and
leaded implantable medical devices, reference is first made to FIG.
1, which shows a conceptual diagram of a cardiac therapy system 2
including an intracardiac medical device 10 that may be configured
for single or dual chamber therapy and implanted in a patient's
heart 8. In some embodiments, the device 10 may be configured for
single-chamber pacing and may, for example, switch between
single-chamber and multiple-chamber pacing (e.g., dual- or
triple-chamber pacing). As used herein, "intracardiac" refers to a
device configured to be implanted entirely within a patient's
heart, for example, to provide cardiac therapy. The device 10 is
shown implanted in the right atrium (RA) of the patient's heart 8
in a target implant region 4. The device 10 may include one or more
fixation members 20 that anchor a distal end of the device against
the atrial endocardium in a target implant region 4. The target
implant region 4 may lie between the His bundle 5 (or bundle of
His) and the coronary sinus 3 and may be adjacent the tricuspid
valve 6. The device 10 may be described as a ventricle-from-atrium
(VfA) device, which may sense or provide therapy to one or both
ventricles (e.g., right ventricle, left ventricle, or both
ventricles, depending on the circumstances) while being generally
disposed in the right atrium. In particular, the device 10 may
include a tissue-piercing electrode that may be implanted in the
basal region, septal region, or basal-septal region of the left
ventricular myocardium of the patient's heart from the triangle of
Koch region of the right atrium through the right-atrial
endocardium and central fibrous body.
[0048] The device 10 may be described as a leadless implantable
medical device. As used herein, "leadless" refers to a device being
free of a lead extending out of the patient's heart 8. In other
words, a leadless device may have a lead that does not extend from
outside of the patient's heart to the inside of the patient's
heart. Some leadless devices may be introduced through a vein, but
once implanted, the device is free of, or may not include, any
transvenous lead and may be configured to provide cardiac therapy
without using any transvenous lead. Further, a leadless VfA device,
in particular, does not use a lead to operably connect to an
electrode in the ventricle when a housing of the device is
positioned in the atrium. Additionally, a leadless electrode may be
coupled to the housing of the medical device without using a lead
between the electrode and the housing.
[0049] The device 10 may include a dart electrode assembly 12
defining, or having, a straight shaft extending from the distal end
region of device 10. The dart electrode assembly 12 may be placed,
or at least configured to be placed, through the atrial myocardium
and the central fibrous body and into the ventricular myocardium
14, or along the ventricular septum, without perforating entirely
through the ventricular endocardial or epicardial surfaces. The
dart electrode assembly 12 may carry, or include, an electrode at
the distal end region of the shaft such that the electrode may be
positioned within the ventricular myocardium for sensing
ventricular signals and delivering ventricular pulses (e.g., to
depolarize the left ventricle to initiate a contraction of the left
ventricle). In some examples, the electrode at the distal end
region of the shaft is a cathode electrode provided for use in a
bipolar electrode pair for pacing and sensing. While the implant
region 4 as illustrated may enable one or more electrodes of the
dart electrode assembly 12 to be positioned in the ventricular
myocardium, it is recognized that a device having the aspects
disclosed herein may be implanted at other locations for multiple
chamber pacing (e.g., dual- or triple-chamber pacing),
single-chamber pacing with multiple chamber sensing, single-chamber
pacing and/or sensing, or other clinical therapy and applications
as appropriate.
[0050] It is to be understood that although device 10 is described
herein as including a single dart electrode assembly, the device 10
may include more than one dart electrode assembly placed, or
configured to be placed, through the atrial myocardium and the
central fibrous body, and into the ventricular myocardium 14, or
along the ventricular septum, without perforating entirely through
the ventricular endocardial or epicardial surfaces. Additionally,
each dart electrode assembly may carry, or include, more than a
single electrode at the distal end region, or along other regions
(e.g., proximal or central regions), of the shaft.
[0051] The cardiac therapy system 2 may also include a separate
medical device 50 (depicted diagrammatically in FIG. 1), which may
be positioned outside the patient's heart 8 (e.g., subcutaneously)
and may be operably coupled to the patient's heart 8 to deliver
cardiac therapy thereto. In one example, separate medical device 50
may be an extravascular ICD. In some embodiments, an extravascular
ICD may include a defibrillation lead including, or carrying, a
defibrillation electrode. A therapy vector may exist between the
defibrillation electrode on the defibrillation lead and a housing
electrode of the ICD. Further, one or more electrodes of the ICD
may also be used for sensing electrical signals related to the
patient's heart 8. The ICD may be configured to deliver shock
therapy including one or more defibrillation or cardioversion
shocks. For example, if an arrhythmia is sensed, the ICD may send a
pulse via the electrical lead wires to shock the heart and restore
its normal rhythm. In some examples, the ICD may deliver shock
therapy without placing electrical lead wires within the heart or
attaching electrical wires directly to the heart (subcutaneous
ICDs). Examples of extravascular, subcutaneous ICDs that may be
used with the system 2 described herein may be described in U.S.
Pat. No. 9,278,229 (Reinke et al.), issued 8 Mar. 2016, which is
incorporated herein by reference in its entirety.
[0052] In the case of shock therapy (e.g., defibrillation shocks
provided by the defibrillation electrode of the defibrillation
lead), the separate medical device 50 (e.g., extravascular ICD) may
include a control circuit that uses a therapy delivery circuit to
generate defibrillation shocks having any of a number of waveform
properties, including leading-edge voltage, tilt, delivered energy,
pulse phases, and the like. The therapy delivery circuit may, for
instance, generate monophasic, biphasic, or multiphasic waveforms.
Additionally, the therapy delivery circuit may generate
defibrillation waveforms having different amounts of energy. For
example, the therapy delivery circuit may generate defibrillation
waveforms that deliver a total of between approximately 60-80
Joules (J) of energy for subcutaneous defibrillation.
[0053] The separate medical device 50 may further include a sensing
circuit. The sensing circuit may be configured to obtain electrical
signals sensed via one or more combinations of electrodes and to
process the obtained signals. The components of the sensing circuit
may include analog components, digital components, or a combination
thereof. The sensing circuit may, for example, include one or more
sense amplifiers, filters, rectifiers, threshold detectors,
analog-to-digital converters (ADCs), or the like. The sensing
circuit may convert the sensed signals to digital form and provide
the digital signals to the control circuit for processing and/or
analysis. For example, the sensing circuit may amplify signals from
sensing electrodes and may convert the amplified signals to
multi-bit digital signals by an ADC, and then provide the digital
signals to the control circuit. In one or more embodiments, the
sensing circuit may also compare processed signals to a threshold
to detect the existence of atrial or ventricular depolarizations
(e.g., P- or R-waves) and indicate the existence of the atrial
depolarization (e.g., P-waves) or ventricular depolarizations
(e.g., R-waves) to the control circuit.
[0054] The device 10 and the separate medical device 50 may
cooperate to provide cardiac therapy to the patient's heart 8. For
example, the device 10 and the separate medical device 50 may be
used to detect tachycardia, monitor tachycardia, and/or provide
tachycardia-related therapy. For example, the device 10 may
communicate with the separate medical device 50 wirelessly to
trigger shock therapy using the separate medical device 50. As used
herein, "wirelessly" refers to an operative coupling or connection
without using a metal conductor between the device 10 and the
separate medical device 50. In one example, wireless communication
may use a distinctive, signaling, or triggering electrical-pulse
provided by the device 10 that conducts through the patient's
tissue and is detectable by the separate medical device 50. In
another example, wireless communication may use a communication
interface (e.g., an antenna) of the device 10 to provide
electromagnetic radiation that propagates through patient's tissue
and is detectable, for example, using a communication interface
(e.g., an antenna) of the separate medical device 50.
[0055] With reference to FIG. 2, a cardiac therapy system 402 may
include a leaded medical device 408 including one, or a single,
implantable lead 410 having a tissue-piercing electrode assembly 12
coupled to a distal end region of the lead and implanted inside the
patient's heart 8. The housing 420 of the leaded medical device 408
may be implanted and positioned outside of the patient's heart 8
and be configured to calibrate pacing therapy and/or deliver pacing
therapy. The lead 410 may include a right-atrial electrode, and the
device 408 may operate as a dual-channel capable device (e.g.,
pacing and/or sensing in both the right atrium and left ventricle).
In some embodiments, the lead 410 may not include a right-atrial
electrode. In other words, the leaded medical device 408 may be a
single channel device, which may be used for asynchronous,
triggered, or another type of single-channel pacing. The leaded
medical device 408, using the lead 410, may sense activity or
deliver pacing to the left ventricle (LV) when the tissue-piercing
electrode assembly 12 is implanted, for example, in the same or
similar manner as described with respect to FIG. 1.
[0056] With reference to FIG. 3, a cardiac therapy system 404 may
include a leaded medical device 418 similar to the leaded medical
device 408 of FIG. 2, except that the device 418 includes two
implantable leads 410, 412. In particular, the implantable lead 412
may include an electrode (e.g., a right-atrial electrode) coupled
to a distal end region of the lead 412 and may be implanted in a
different location than lead 410. In some embodiments, lead 412 is
implanted in a different region of the right atrium. In some
embodiments, each lead 410, 412 may contribute one channel of a
dual-channel device 418. For example, lead 410 may sense activity
or deliver pacing to the left ventricle (LV) when the
tissue-piercing electrode of the tissue-piercing electrode assembly
12 is implanted, for example, in the same or similar manner as
described with respect to FIG. 1, and lead 412 may sense activity
or deliver pacing to the right atrium (RA).
[0057] With reference to FIG. 4, a cardiac therapy system 406 may
include a leaded medical device 428 similar to the leaded medical
device 418 of FIG. 3 except that device 428 includes three
implantable leads 410, 412, 414. In particular, implantable lead
414 may include an electrode (e.g., a right ventricular electrode)
coupled to a distal end region of the lead 414 and may be implanted
in a different location than leads 410, 412. As illustrated,
implantable lead 414 extends from the right atrium (RA) to the
right ventricle (RV) through tricuspid valve 6. In some
embodiments, lead 414 is implanted in a region of the right
ventricle. In some embodiments, each lead 410, 412, 414 may
contribute one channel to a multi-channel device 428. For example,
lead 410 may sense activity or deliver pacing to the left ventricle
(LV) when the tissue-piercing electrode assembly 12 is implanted,
for example, in the same or similar manner as described with
respect to FIG. 1, lead 412 may sense activity from the delivery of
pacing to the RA, and lead 414 may sense activity or deliver pacing
to the RV.
[0058] In some embodiments, a pacing delay between the RV electrode
on lead 414 to pace the RV and the LV electrode on lead 410 to pace
the LV (e.g., RV-LV pacing delay, or more generally, VV pacing
delay) may be calibrated or optimized, for example, using a
separate medical device, such as an electrode apparatus (e.g., ECG
belt). Various methods may be used to calibrate or optimize the VV
delay. In some embodiments, the medical device 428 may be used to
test pacing at a plurality of different VV delays. For example, the
RV may be paced ahead of the LV by about 80, 60, 40, and 20
milliseconds (ms) and the LV may be paced ahead of the RV by about
80, 60, 40, and 20 ms, as well as simultaneous RV-LV pacing (e.g.,
about 0 ms VV pacing delay). The medical device 428 may then be
configured, for example, automatically, to select a VV pacing delay
that, when used for pacing, corresponds to a minimal electrical
dyssynchrony measured using the electrode apparatus. The test
pacing at different VV pacing delays may be performed using a
particular AV delay, such as a nominal AV delay set by the medical
device 428 or at a predetermined optimal AV delay based on patient
characteristics.
[0059] FIG. 5 is an enlarged conceptual diagram of the intracardiac
medical device 10 of FIG. 1 and anatomical structures of the
patient's heart 8. In particular, the device 10 is configured to
sense electrical activity and/or deliver pacing therapy. The
intracardiac device 10 may include a housing 30. The housing 30 may
define a hermetically-sealed internal cavity in which internal
components of the device 10 reside, such as a sensing circuit,
therapy delivery circuit, control circuit, memory, telemetry
circuit, other optional sensors, and a power source as generally
described in conjunction with FIG. 8. The housing 30 may be formed
from an electrically conductive material including titanium or
titanium alloy, stainless steel, MP35N (a non-magnetic
nickel-cobalt-chromium-molybdenum alloy), platinum alloy, or other
bio-compatible metal or metal alloy. In other examples, the housing
30 may be formed from a non-conductive material including ceramic,
glass, sapphire, silicone, polyurethane, epoxy, acetyl co-polymer
plastics, polyether ether ketone (PEEK), a liquid crystal polymer,
or other biocompatible polymer.
[0060] In at least one embodiment, the housing 30 may be described
as extending between a distal end region 32 and a proximal end
region 34 in a generally cylindrical shape to facilitate catheter
delivery. In other embodiments, the housing 30 may be prismatic or
any other shape to perform the functionality and utility described
herein. The housing 30 may include a delivery tool interface member
26, e.g., at the proximal end region 34, for engaging with a
delivery tool during implantation of the device 10.
[0061] All or a portion of the housing 30 may function as an
electrode during cardiac therapy, for example, in sensing and/or
pacing. In the example shown, the housing-based electrode 24 is
shown to circumscribe a proximal portion (e.g., closer to the
proximal end region 34 than the distal end region 32) of the
housing 30. When the housing 30 is formed from an electrically
conductive material, such as a titanium alloy or other examples
listed above, portions of the housing 30 may be electrically
insulated by a non-conductive material, such as a coating of
parylene, polyurethane, silicone, epoxy, or other biocompatible
polymer, leaving one or more discrete areas of conductive material
exposed to define the proximal housing-based electrode 24. When the
housing 30 is formed from a non-conductive material, such as a
ceramic, glass or polymer material, an electrically conductive
coating or layer, such as a titanium, platinum, stainless steel, or
alloys thereof, may be applied to one or more discrete areas of the
housing 30 to form the proximal housing-based electrode 24. In
other examples, the proximal housing-based electrode 24 may be a
component, such as a ring electrode, that is mounted or assembled
onto the housing 30. The proximal housing-based electrode 24 may be
electrically coupled to internal circuitry of the device 10, e.g.,
via the electrically-conductive housing 30 or an electrical
conductor when the housing 30 is a non-conductive material.
[0062] In the example shown, the proximal housing-based electrode
24 is located nearer to the housing proximal end region 34 than the
housing distal end region 32 and is therefore referred to as a
"proximal housing-based electrode" 24. In other examples, however,
the housing-based electrode 24 may be located at other positions
along the housing 30, e.g., more distal relative to the position
shown.
[0063] At the distal end region 32, the device 10 may include a
distal fixation and electrode assembly 36, which may include one or
more fixation members 20 and one or more dart electrode assemblies
12 of equal or unequal length. In one example, a single dart
electrode assembly 12 includes a shaft 40 extending distally away
from the housing distal end region 32 and one or more electrode
elements, such as a tip electrode 42 at or near the free, distal
end region of the shaft 40. The tip electrode 42 may have a conical
or hemispherical distal tip with a relatively narrow tip-diameter
(e.g., less than about 1 millimeter (mm)) for penetrating into and
through tissue layers without using a sharpened tip or needle-like
tip having sharpened or beveled edges.
[0064] The shaft 40 of the dart electrode assembly 12 may be a
normally straight member and may be rigid. In other embodiments,
the shaft 40 may be described as being relatively stiff but still
possessing limited flexibility in lateral directions. Further, the
shaft 40 may be non-rigid to allow some lateral flexing with heart
motion. However, in a relaxed state, when not subjected to any
external forces, the shaft 40 may maintain a straight position as
shown to hold the tip electrode 42 spaced apart from the housing
distal end region 32 at least by the height 47 of the shaft 40. In
other words, the dart electrode assembly 12 may be described as
resilient.
[0065] The dart electrode assembly 12 may be configured to pierce
through one or more tissue layers to position the tip electrode 42
within a desired tissue layer, e.g., the ventricular myocardium. As
such, the height 47, or length, of the shaft 40 may correspond to
the expected pacing site depth, and the shaft 40 may have a
relatively high compressive strength along its longitudinal axis to
resist bending in a lateral or radial direction when pressed
against the implant region 4. If a second dart electrode assembly
12 is employed, its length may be unequal to the expected pacing
site depth and may be configured to act as an indifferent electrode
for delivering of pacing energy to the tissue. A longitudinal axial
force may be applied against the tip electrode 42, e.g., by
applying a longitudinal pushing force to the proximal end region 34
of the housing 30, to advance the dart electrode assembly 12 into
the tissue within the target implant region. The shaft 40 may be
described as longitudinally non-compressive and/or elastically
deformable in lateral or radial directions when subjected to
lateral or radial forces to allow temporary flexing, e.g., with
tissue motion, but may return to its normally straight position
when lateral forces diminish. When the shaft 40 is not exposed to
any external force, or to only a force along its longitudinal
central axis, the shaft 40 may retain a straight, linear position
as shown.
[0066] The one or more fixation members 20 may be described as one
or more "tines" having a normally curved position. The tines may be
held in a distally extended position within a delivery tool. The
distal tips of tines may penetrate the heart tissue to a limited
depth before elastically curving back proximally into the normally
curved position (shown) upon release from the delivery tool.
Further, the fixation members 20 may include one or more aspects
described in, for example, U.S. Pat. No. 9,675,579 (Grubac et al.),
issued 13 Jun. 2017, and U.S. Pat. No. 9,119,959 (Rys et al.),
issued 1 Sep. 2015, each of which is incorporated herein by
reference in its entirety.
[0067] In some examples, the distal fixation and electrode assembly
36 includes a distal housing-based electrode 22. In the case of
using the device 10 as a pacemaker for multiple chamber pacing
(e.g., dual- or triple-chamber pacing) and sensing, the tip
electrode 42 may be used as a cathode electrode paired with the
proximal housing-based electrode 24 serving as a return anode
electrode. Alternatively, the distal housing-based electrode 22 may
serve as a return anode electrode paired with tip electrode 42 for
sensing ventricular signals and delivering ventricular pacing
pulses. In other examples, the distal housing-based electrode 22
may be a cathode electrode for sensing atrial signals and
delivering pacing pulses to the atrial myocardium in the target
implant region 4. When the distal housing-based electrode 22 serves
as an atrial cathode electrode, the proximal housing-based
electrode 24 may serve as the return anode paired with the tip
electrode 42 for ventricular pacing and sensing and as the return
anode paired with the distal housing-based electrode 22 for atrial
pacing and sensing.
[0068] As shown in this illustration, the target implant region 4
in some pacing applications is along the atrial endocardium 18,
generally inferior to the AV node 15 and the His bundle 5. The dart
electrode assembly 12 may at least partially define the height 47,
or length, of the shaft 40 for penetrating through the atrial
endocardium 18 in the target implant region 4, through the central
fibrous body 16, and into the ventricular myocardium 14 without
perforating through the ventricular endocardial surface 17. When
the height 47, or length, of the dart electrode assembly 12 is
fully advanced into the target implant region 4, the tip electrode
42 may rest within the ventricular myocardium 14, and the distal
housing-based electrode 22 may be positioned in intimate contact
with or close proximity to the atrial endocardium 18. The dart
electrode assembly 12 may have a total combined height 47, or
length, of the tip electrode 42 and the shaft 40 from about 3 mm to
about 8 mm in various examples. The diameter of the shaft 40 may be
less than about 2 mm, and may be about 1 mm or less, or even about
0.6 mm or less.
[0069] The device 10 may include an acoustic or motion detector 11
within the housing 30. The acoustic or motion detector 11 may be
operably coupled to one or more a control circuit 80 (FIG. 8), a
sensing circuit 86 (FIG. 8), or therapy delivery circuit 84 (FIG.
8). In some embodiments, the acoustic or motion detector 11 may be
used with methods 600, 650, or 800 as shown in FIGS. 10-12. The
acoustic or motion detector 11 may be used to monitor mechanical
activity, such as atrial mechanical activity (e.g., an atrial
contraction) and/or ventricular mechanical activity (e.g., a
ventricular contraction). In some embodiments, the acoustic or
motion detector 11 may be used to detect right-atrial mechanical
activity. A non-limiting example of an acoustic or motion detector
11 includes an accelerometer or microphone. In some embodiments,
the mechanical activity detected by the acoustic or motion detector
11 may be used to supplement or replace electrical activity
detected by one or more of the electrodes of the device 10. For
example, the acoustic or motion detector 11 may be used in addition
to, or as an alternative to, the proximal housing-based electrode
24.
[0070] The acoustic or motion detector 11 may also be used for rate
response detection or to provide a rate-responsive 1 MB. Various
techniques related to rate response may be described in U.S. Pat.
No. 5,154,170 (Bennett et al.), issued Oct. 13, 1992, entitled
"Optimization for rate responsive cardiac pacemaker," and U.S. Pat.
No. 5,562,711 (Yerich et al.), issued Oct. 8, 1996, entitled
"Method and apparatus for rate-responsive cardiac pacing," each of
which is incorporated herein by reference in its entirety.
[0071] In various embodiments, acoustic or motion detector 11 (or
motion sensor) may be used as an HS sensor and may be implemented
as a microphone or a 1-, 2- or 3-axis accelerometer. In one
embodiment, the acoustical sensor is implemented as a piezoelectric
crystal mounted within an implantable medical device housing and
responsive to the mechanical motion associated with heart sounds.
The piezoelectric crystal may be a dedicated HS sensor or may be
used for multiple functions. In the illustrative embodiment shown,
the acoustical sensor is embodied as a piezoelectric crystal that
is also used to generate a patient alert signal in the form of a
perceptible vibration of the IMD housing. Upon detecting an alert
condition, control circuit 80 may cause patient alert control
circuitry to generate an alert signal by activating the
piezoelectric crystal.
[0072] The control circuit may be used to control whether the
piezoelectric crystal is used in a "listening mode" to sense HS
signals by HS sensing circuitry or in an "output mode" to generate
a patient alert. During patient alert generation, HS sensing
circuitry may be temporarily decoupled from the HS sensor by
control circuitry.
[0073] Examples of other embodiments of acoustical sensors that may
be adapted for implementation with the techniques of the present
disclosure may be described generally in U.S. Pat. No. 4,546,777
(Groch, et al.), U.S. Pat. No. 6,869,404 (Schulhauser, et al.),
U.S. Pat. No. 5,554,177 (Kieval, et al.), and U.S. Pat. No.
7,035,684 (Lee, et al.), each of which is incorporated herein by
reference in its entirety.
[0074] Various types of acoustical sensors may be used. The
acoustical sensor may be any implantable or external sensor
responsive to one or more of the heart sounds generated as
described in the foregoing and thereby produces an analog
electrical signal correlated in time and amplitude to the heart
sounds. The analog signal may be then be processed, which may
include digital conversion, by the HS sensing module to obtain HS
parameters, such as amplitudes or relative time intervals, as
derived by HS sensing module or control circuit 80. The acoustical
sensor and HS sensing module may be incorporated in an IMD capable
of delivering CRT or another cardiac therapy being optimized or may
be implemented in a separate device having wired or wireless
communication with IMD or an external programmer or computer used
during a pace-parameter optimization procedure as described
herein.
[0075] FIG. 6 is a two-dimensional (2D) ventricular map 300 of a
patient's heart (e.g., a top-down view) showing the left ventricle
320 in a standard 17 segment view and the right ventricle 322. The
map 300 includes a plurality of areas 326 corresponding to
different regions of a human heart. As illustrated, the areas 326
are numerically labeled 1-17 (e.g., which correspond to 17 segments
of the left ventricle of a human heart). Areas 326 of the map 300
may include basal anterior area 1, basal anteroseptal area 2, basal
inferoseptal area 3, basal inferior area 4, basal inferolateral
area 5, basal anterolateral area 6, mid-anterior area 7,
mid-anteroseptal area 8, mid-inferoseptal area 9, mid-inferior area
10, mid-inferolateral area 11, mid-anterolateral area 12, apical
anterior area 13, apical septal area 14, apical inferior area 15,
apical lateral area 16, and apex area 17. The inferoseptal and
anteroseptal areas of the right ventricle 322 are also illustrated,
as well as the right bundle branch (RBB) and left bundle branch
(LBB).
[0076] In some embodiments, any of the tissue-piercing electrodes
of the present disclosure may be implanted in the basal region,
septal region, or basal-septal region of the left ventricular
myocardium of the patient's heart. In particular, the
tissue-piercing electrode may be implanted from the triangle of
Koch region of the right atrium through the right-atrial
endocardium and central fibrous body.
[0077] Once implanted, the tissue-piercing electrode may be
positioned in the target implant region 4 (FIGS. 1-5), such as the
basal region, septal region, or basal-septal region of the left
ventricular myocardium. With reference to map 300, the basal region
includes one or more of the basal anterior area 1, basal
anteroseptal area 2, basal inferoseptal area 3, basal inferior area
4, mid-anterior area 7, mid-anteroseptal area 8, mid-inferoseptal
area 9, and mid-inferior area 10. With reference to map 300, the
septal region includes one or more of the basal anteroseptal area
2, basal anteroseptal area 3, mid-anteroseptal area 8,
mid-inferoseptal area 9, and apical septal area 14.
[0078] In some embodiments, the tissue-piercing electrode may be
positioned in the basal septal region of the left ventricular
myocardium when implanted. The basal septal region may include one
or more of the basal anteroseptal area 2, basal inferoseptal area
3, mid-anteroseptal area 8, and mid-inferoseptal area 9.
[0079] In some embodiments, the tissue-piercing electrode may be
positioned in the inferior/posterior basal septal region of the
left ventricular myocardium when implanted. In some cases, the
inferior/posterior basal septal region may be described as the high
inferior/posterior basal septal region. In some embodiments, the
tissue-piercing electrode may be positioned in the posterior
superior process of the left ventricle. In some embodiments, the
tissue-piercing electrode may be positioned in the high
inferior/posterior basal septal region of the left ventricular
myocardium when implanted. The inferior/posterior basal septal
region of the left ventricular myocardium may include a portion of
one or more of the basal inferoseptal area 3 and mid-inferoseptal
area 9 (e.g., the basal inferoseptal area only, the
mid-inferoseptal area only, or both the basal inferoseptal area and
the mid-inferoseptal area). For example, the inferior/posterior
basal septal region may include region 324 illustrated generally as
a dashed-line boundary. As shown, the dashed line boundary
represents an approximation of where the inferior/posterior basal
septal region is located, which may take a somewhat different shape
or size depending on the particular application.
[0080] FIG. 7 is a three-dimensional perspective view of the device
10 capable of calibrating pacing therapy and/or delivering pacing
therapy. As shown, the distal fixation and electrode assembly 36
includes the distal housing-based electrode 22 implemented as a
ring electrode. The distal housing-based electrode 22 may be
positioned in intimate contact with or operative proximity to
atrial tissue when fixation member tines 20a, 20b, and 20c of the
fixation members 20, engage with the atrial tissue. The tines 20a,
20b, and 20c, which may be elastically deformable, may be extended
distally during delivery of device 10 to the implant site. For
example, the tines 20a, 20b, and 20c may pierce the atrial
endocardial surface as the device 10 is advanced out of the
delivery tool and flex back into their normally curved position (as
shown) when no longer constrained within the delivery tool. As the
tines 20a, 20b, and 20c curve back into their normal position, the
fixation member 20 may pull the distal fixation member and
electrode assembly 36 toward the atrial endocardial surface. As the
distal fixation member and electrode assembly 36 is pulled toward
the atrial endocardium, the tip electrode 42 may be advanced
through the atrial myocardium and the central fibrous body and into
the ventricular myocardium. The distal housing-based electrode 22
may then be positioned against the atrial endocardial surface.
[0081] The distal housing-based electrode 22 may include a ring
formed of an electrically conductive material, such as titanium,
platinum, iridium, or alloys thereof. The distal housing-based
electrode 22 may be a single, continuous ring electrode. In other
examples, portions of the ring may be coated with an electrically
insulating coating, e.g., parylene, polyurethane, silicone, epoxy,
or another insulating coating, to reduce the electrically
conductive surface area of the ring electrode. For instance, one or
more sectors of the ring may be coated to separate two or more
electrically conductive exposed surface areas of the distal
housing-based electrode 22. Reducing the electrically conductive
surface area of the distal housing-based electrode 22, e.g., by
covering portions of the electrically conductive ring with an
insulating coating, may increase the electrical impedance of the
distal housing-based electrode 22, and thereby, reduce the current
delivered during a pacing pulse that captures the myocardium, e.g.,
the atrial myocardial tissue. A lower current drain may conserve
the power source, e.g., one or more rechargeable or
non-rechargeable batteries, of the device 10.
[0082] As described above, the distal housing-based electrode 22
may be configured as an atrial cathode electrode for delivering
pacing pulses to the atrial tissue at the implant site in
combination with the proximal housing-based electrode 24 as the
return anode. The electrodes 22 and 24 may be used to sense atrial
P-waves for use in controlling atrial pacing pulses (delivered in
the absence of a sensed P-wave) and for controlling
atrial-synchronized ventricular pacing pulses delivered using the
tip electrode 42 as a cathode and the proximal housing-based
electrode 24 as the return anode. In other examples, the distal
housing-based electrode 22 may be used as a return anode in
conjunction with the cathode tip electrode 42 for ventricular
pacing and sensing.
[0083] FIG. 8 is a block diagram of circuitry that may be enclosed
within the housing 30 (FIG. 7) to provide the functions of
calibrating pacing therapy and/or delivering pacing therapy, using
the device 10 according to one example or within the housings of
any other medical devices described herein (e.g., device 408 of
FIG. 2, device 418 of FIG. 3, device 428 of FIG. 4, or device 710
of FIG. 9). The separate medical device 50 (FIGS. 1-4) may include
some or all the same components, which may be configured in a
similar manner. The electronic circuitry enclosed within housing 30
may include software, firmware, and hardware that cooperatively
monitor atrial and ventricular electrical cardiac signals,
determine when a cardiac therapy is necessary, and/or deliver
electrical pulses to the patient's heart according to programmed
therapy mode and pulse control parameters. The electronic circuitry
may include a control circuit 80 (e.g., including processing
circuitry), a memory 82, a therapy delivery circuit 84, a sensing
circuit 86, and/or a telemetry circuit 88. In some examples, the
device 10 includes one or more sensors 90 for producing a signal
that is correlated to a physiological function, state, or condition
of the patient, such as a patient activity sensor, for use in
determining a need for pacing therapy and/or controlling a pacing
rate. For example, one sensor 90 may include an inertial
measurement unit (e.g., accelerometer) to measure motion.
[0084] The power source 98 may provide power to the circuitry of
the device 10 including each of the components 80, 82, 84, 86, 88,
90 as needed. The power source 98 may include one or more energy
storage devices, such as one or more rechargeable or
non-rechargeable batteries. The connections (not shown) between the
power source 98 and each of the components, such as sensors 80, 82,
84, 86, 88, 90, may be understood from the general block diagram
illustrated to one of ordinary skill in the art. For example, the
power source 98 may be coupled to one or more charging circuits
included in the therapy delivery circuit 84 for providing the power
used to charge holding capacitors included in the therapy delivery
circuit 84 that are discharged at appropriate times under the
control of the control circuit 80 for delivering pacing pulses,
e.g., according to a dual chamber pacing mode such as DDI(R). The
power source 98 may also be coupled to components of the sensing
circuit 86, such as sense amplifiers, analog-to-digital converters,
switching circuitry, etc., sensors 90, the telemetry circuit 88,
and the memory 82 to provide power to the various circuits.
[0085] The functional blocks shown represent functionality included
in the device 10 and may include any discrete and/or integrated
electronic circuit components that implement analog, and/or digital
circuits capable of producing the functions attributed to the
medical device 10 herein. The various components may include
processing circuitry, such as an application specific integrated
circuit (ASIC), an electronic circuit, a processor (shared,
dedicated, or group), and memory that execute one or more software
or firmware programs, a combinational logic circuit, state machine,
or other suitable components or combinations of components that
provide the described functionality. The particular form of
software, hardware, and/or firmware employed to implement the
functionality disclosed herein will be determined primarily by the
particular system architecture employed in the medical device and
by the particular detection and therapy delivery methodologies
employed by the medical device.
[0086] The memory 82 may include any volatile, non-volatile,
magnetic, or electrical non-transitory computer-readable storage
media, such as random-access memory (RAM), read-only memory (ROM),
non-volatile RAM (NVRAM), electrically-erasable programmable ROM
(EEPROM), flash memory, or any other memory device. Furthermore,
the memory 82 may include a non-transitory computer-readable media
storing instructions that, when executed by one or more processing
circuits, cause the control circuit 80 and/or other processing
circuitry to calibrate pacing therapy and/or perform a single,
dual, or triple-chamber calibrated pacing therapy (e.g., single or
multiple chamber pacing), or other cardiac therapy functions (e.g.,
sensing or delivering therapy), attributed to the device 10. The
non-transitory computer-readable media storing the instructions may
include any of the media listed above.
[0087] The control circuit 80 may communicate, e.g., via a data
bus, with the therapy delivery circuit 84 and the sensing circuit
86 for sensing cardiac electrical signals and controlling delivery
of cardiac electrical stimulation therapies in response to sensed
cardiac events, e.g., P-waves and R-waves, or the absence thereof.
The tip electrode 42, the distal housing-based electrode 22, and
the proximal housing-based electrode 24 may be electrically coupled
to the therapy delivery circuit 84 for delivering electrical
stimulation pulses to the patient's heart and to the sensing
circuit 86 and for sensing cardiac electrical signals.
[0088] The sensing circuit 86 may include an atrial (A) sensing
channel 87 and a ventricular (V) sensing channel 89. The distal
housing-based electrode 22 and the proximal housing-based electrode
24 may be coupled to the atrial sensing channel 87 for sensing
atrial signals, e.g., P-waves attendant to the depolarization of
the atrial myocardium. In examples that include two or more
selectable distal housing-based electrodes, the sensing circuit 86
may include switching circuitry for selectively coupling one or
more of the available distal housing-based electrodes to cardiac
event detection circuitry included in the atrial sensing channel
87. Switching circuitry may include a switch array, switch matrix,
multiplexer, or any other type of switching device suitable to
selectively couple components of the sensing circuit 86 to selected
electrodes. The tip electrode 42 and the proximal housing-based
electrode 24 may be coupled to the ventricular sensing channel 89
for sensing ventricular signals, e.g., R-waves attendant to the
depolarization of the ventricular myocardium.
[0089] Each of the atrial sensing channel 87 and the ventricular
sensing channel 89 may include cardiac event detection circuitry
for detecting P-waves and R-waves, respectively, from the cardiac
electrical signals received by the respective sensing channels. The
cardiac event detection circuitry included in each of the channels
87 and 89 may be configured to amplify, filter, digitize, and
rectify the cardiac electrical signal received from the selected
electrodes to improve the signal quality for detecting cardiac
electrical events. The cardiac event detection circuitry within
each channel 87 and 89 may include one or more sense amplifiers,
filters, rectifiers, threshold detectors, comparators,
analog-to-digital converters (ADCs), timers, or other analog or
digital components. A cardiac event sensing threshold, e.g., a
P-wave sensing threshold and an R-wave sensing threshold, may be
automatically adjusted by each respective sensing channel 87 and 89
under the control of the control circuit 80, e.g., based on timing
intervals and sensing threshold values determined by the control
circuit 80, stored in the memory 82, and/or controlled by hardware,
firmware, and/or software of the control circuit 80 and/or the
sensing circuit 86.
[0090] Upon detecting a cardiac electrical event based on a sensing
threshold crossing, the sensing circuit 86 may produce a sensed
event signal that is passed to the control circuit 80. For example,
the atrial sensing channel 87 may produce a P-wave sensed event
signal in response to a P-wave sensing threshold crossing. The
ventricular sensing channel 89 may produce an R-wave sensed event
signal in response to an R-wave sensing threshold crossing. The
sensed event signals may be used by the control circuit 80 for
setting pacing escape interval timers that control the basic time
intervals used for scheduling cardiac pacing pulses. A sensed event
signal may trigger or inhibit a pacing pulse depending on the
particular programmed pacing mode. For example, a P-wave sensed
event signal received from the atrial sensing channel 87 may cause
the control circuit 80 to inhibit a scheduled atrial pacing pulse
and schedule a ventricular pacing pulse at a programmed
atrioventricular (AV) pacing interval. If an R-wave is sensed
before the AV pacing interval expires, the ventricular pacing pulse
may be inhibited. If the AV pacing interval expires before the
control circuit 80 receives an R-wave sensed event signal from the
ventricular sensing channel 89, the control circuit 80 may use the
therapy delivery circuit 84 to deliver the scheduled ventricular
pacing pulse synchronized to the sensed P-wave.
[0091] In some examples, the device 10 may be configured to deliver
a variety of pacing therapies including bradycardia pacing, cardiac
resynchronization therapy, post-shock pacing, and/or
tachycardia-related therapy, such as ATP, among others. For
example, the device 10 may be configured to detect non-sinus
tachycardia and deliver ATP. The control circuit 80 may determine
cardiac event time intervals, e.g., P-P intervals between
consecutive P-wave sensed event signals received from the atrial
sensing channel 87, R-R intervals between consecutive R-wave sensed
event signals received from the ventricular sensing channel 89, and
P-R and/or R-P intervals received between P-wave sensed event
signals and R-wave sensed event signals. These intervals may be
compared to tachycardia detection intervals for detecting non-sinus
tachycardia. Tachycardia may be detected in a given heart chamber
based on a threshold number of tachycardia detection intervals
being detected.
[0092] The therapy delivery circuit 84 may include atrial pacing
circuit 83 and ventricular pacing circuit 85. Each pacing circuit
83, 85 may include charging circuitry, one or more charge storage
devices such as one or more low voltage holding capacitors, an
output capacitor, and/or switching circuitry that controls when the
holding capacitor(s) are charged and discharged across the output
capacitor to deliver a pacing pulse to the pacing electrode vector
coupled to respective pacing circuits 83, 85. The tip electrode 42
and the proximal housing-based electrode 24 may be coupled to the
ventricular pacing circuit 85 as a bipolar cathode and anode pair
for delivering ventricular pacing pulses, e.g., upon expiration of
an AV or VV pacing interval set by the control circuit 80 for
providing atrial-synchronized ventricular pacing and a basic lower
ventricular pacing rate.
[0093] The atrial pacing circuit 83 may be coupled to the distal
housing-based electrode 22 and the proximal housing-based electrode
24 to deliver atrial pacing pulses. The control circuit 80 may set
one or more atrial pacing intervals according to a programmed lower
pacing rate or a temporary lower rate set according to a
rate-responsive sensor-indicated pacing rate. Atrial pacing circuit
may be controlled to deliver an atrial pacing pulse if the atrial
pacing interval expires before a P-wave sensed event signal is
received from the atrial sensing channel 87. The control circuit 80
starts an AV pacing interval in response to a delivered atrial
pacing pulse to provide synchronized multiple chamber pacing (e.g.,
dual- or triple-chamber pacing).
[0094] Charging of a holding capacitor of the atrial or ventricular
pacing circuit 83, 85 to a programmed pacing voltage amplitude and
discharging of the capacitor for a programmed pacing pulse width
may be performed by the therapy delivery circuit 84 according to
control signals received from the control circuit 80. For example,
a pace timing circuit included in the control circuit 80 may
include programmable digital counters set by a microprocessor of
the control circuit 80 for controlling the basic pacing time
intervals associated with various single-chamber or
multiple-chamber pacing (e.g., dual- or triple-chamber pacing)
modes or anti-tachycardia pacing sequences. The microprocessor of
the control circuit 80 may also set the amplitude, pulse width,
polarity, or other characteristics of the cardiac pacing pulses,
which may be based on programmed values stored in the memory
82.
[0095] The device 10 may include other sensors 90 for sensing
signals from the patient for use in determining a need for and/or
controlling electrical stimulation therapies delivered by the
therapy delivery circuit 84. In some examples, a sensor indicative
of a need for increased cardiac output may include a patient
activity sensor, such as an accelerometer. An increase in the
metabolic demand of the patient due to increased activity as
indicated by the patient activity sensor may be determined by the
control circuit 80 for use in determining a sensor-indicated pacing
rate.
[0096] Control parameters utilized by the control circuit 80 for
sensing cardiac events and controlling pacing therapy delivery may
be programmed into the memory 82 via the telemetry circuit 88,
which may also be described as a communication interface. The
telemetry circuit 88 includes a transceiver and antenna for
communicating with an external device, such as a programmer or home
monitor, using radio frequency communication or other communication
protocols. The control circuit 80 may use the telemetry circuit 88
to receive downlink telemetry from and send uplink telemetry to the
external device. In some cases, the telemetry circuit 88 may be
used to transmit and receive communication signals to/from another
medical device implanted in the patient.
[0097] FIG. 9 is a three-dimensional perspective view of another
leadless intracardiac medical device 710 that may be configured for
calibrating pacing therapy and/or delivering pacing therapy for
single or multiple chamber cardiac therapy (e.g., dual- or
triple-chamber cardiac therapy) according to another example. The
device 710 may include a housing 730 having an outer sidewall 735,
shown as a cylindrical outer sidewall, extending from a housing
distal end region 732 to a housing proximal end region 734. The
housing 730 may enclose electronic circuitry configured to perform
single- or multiple-chamber cardiac therapy, including atrial and
ventricular cardiac electrical signal sensing and pacing the atrial
and ventricular chambers. The delivery tool interface member 726 is
shown on the housing proximal end region 734.
[0098] A distal fixation and electrode assembly 736 may be coupled
to the housing distal end region 732. The distal fixation and
electrode assembly 736 may include an electrically insulative
distal member 772 coupled to the housing distal end region 732. The
tissue-piercing electrode assembly 712 extends away from the
housing distal end region 732, and multiple non-tissue piercing
electrodes 722 may be coupled directly to the insulative distal
member 772. The tissue-piercing electrode assembly 712 extends in a
longitudinal direction away from the housing distal end region 732
and may be coaxial with the longitudinal center axis 731 of the
housing 730.
[0099] The distal tissue-piercing electrode assembly 712 may
include an electrically insulated shaft 740 and a tip electrode 742
(e.g., tissue-piercing electrode). In some examples, the
tissue-piercing electrode assembly 712 is an active fixation member
including a helical shaft 740 and a distal cathode tip electrode
742. The helical shaft 740 may extend from a shaft distal end
region 743 to a shaft proximal end region 741, which may be
directly coupled to the insulative distal member 772. The helical
shaft 740 may be coated with an electrically insulating material,
e.g., parylene or other examples listed herein, to avoid sensing or
stimulation of cardiac tissue along the shaft length. The tip
electrode 742 is at the shaft distal end region 743 and may serve
as a cathode electrode for delivering ventricular pacing pulses and
sensing ventricular electrical signals using the proximal
housing-based electrode 724 as a return anode when the tip
electrode 742 is advanced into ventricular tissue. The proximal
housing-based electrode 724 may be a ring electrode circumscribing
the housing 730 and may be defined by an uninsulated portion of the
longitudinal sidewall 735. Other portions of the housing 730 not
serving as an electrode may be coated with an electrically
insulating material as described above in conjunction with FIG.
7.
[0100] Using two or more tissue-piercing electrodes (e.g., of any
type) penetrating into the LV myocardium may be used for more
localized pacing capture and may mitigate ventricular pacing spikes
affecting capturing atrial tissue. In some embodiments, multiple
tissue-piercing electrodes may include two or more dart-type
electrode assemblies (e.g., electrode assembly 12 of FIG. 7), a
helical-type electrode (e.g., electrode assembly 712) Non-limiting
examples of multiple tissue-piercing electrodes include two dart
electrode assemblies, a helix electrode with a dart electrode
assembly extending therethrough (e.g., through the center), or dual
intertwined helixes. Multiple tissue-piercing electrodes may also
be used for bipolar or multi-polar pacing.
[0101] In some embodiments, one or more tissue-piercing electrodes
(e.g., of any type) that penetrate into the LV myocardium may be a
multi-polar tissue-piercing electrode. A multi-polar
tissue-piercing electrode may include one or more electrically
active and electrically separate elements, which may enable bipolar
or multi-polar pacing from one or more tissue-piercing
electrodes.
[0102] Multiple non-tissue piercing electrodes 722 may be provided
along a periphery of the insulative distal member 772, peripheral
to the tissue-piercing electrode assembly 712. The insulative
distal member 772 may define a distal-facing surface 738 of the
device 710 and a circumferential surface 739 that circumscribes the
device 710 adjacent to the housing longitudinal sidewall 735.
Non-tissue piercing electrodes 722 may be formed of an electrically
conductive material, such as titanium, platinum, iridium, or alloys
thereof. In the illustrated embodiment, six non-tissue piercing
electrodes 722 are spaced apart radially at equal distances along
the outer periphery of insulative distal member 772. However, two
or more non-tissue piercing electrodes 722 may be provided.
[0103] Non-tissue piercing electrodes 722 may be discrete
components each retained within a respective recess 774 in the
insulative member 772 sized and shaped to mate with the non-tissue
piercing electrode 722. In other examples, the non-tissue piercing
electrodes 722 may each be an uninsulated, exposed portion of a
unitary member mounted within or on the insulative distal member
772. Intervening portions of the unitary member not functioning as
an electrode may be insulated by the insulative distal member 772
or, if exposed to the surrounding environment, may be coated with
an electrically insulating coating, e.g., parylene, polyurethane,
silicone, epoxy, or another insulating coating.
[0104] When the tissue-piercing electrode assembly 712 is advanced
into cardiac tissue, at least one non-tissue piercing electrode 722
may be positioned against, in intimate contact with, or in
operative proximity to, a cardiac tissue surface for delivering
pulses and/or sensing cardiac electrical signals produced by the
patient's heart. For example, non-tissue piercing electrodes 722
may be positioned in contact with right-atrial endocardial tissue
for pacing and sensing in the atrium when the tissue-piercing
electrode assembly 712 is advanced into the atrial tissue and
through the central fibrous body until the distal tip electrode 742
is positioned in direct contact with ventricular tissue, e.g.,
ventricular myocardium and/or a portion of the ventricular
conduction system.
[0105] Non-tissue piercing electrodes 722 may be coupled to the
therapy delivery circuit 84 and the sensing circuit 86 (see FIG. 8)
enclosed by the housing 730 to function collectively as a cathode
electrode for delivering atrial pacing pulses and for sensing
atrial electrical signals, e.g., P-waves, in combination with the
proximal housing-based electrode 724 as a return anode. Switching
circuitry included in the sensing circuit 86 may be activated under
the control of the control circuit 80 to couple one or more of the
non-tissue piercing electrodes to the atrial sensing channel 87.
Distal, non-tissue piercing electrodes 722 may be electrically
isolated from each other so that each individual one of the
electrodes 722 may be individually selected by switching circuitry
included in the therapy delivery circuit 84 to serve alone or in a
combination of two or more of the electrodes 722 as an atrial
cathode electrode. Switching circuitry included in the therapy
delivery circuit 84 may be activated under the control of the
control circuit 80 to couple one or more of the non-tissue piercing
electrodes 722 to the atrial pacing circuit 83. Two or more of the
non-tissue piercing electrodes 722 may be selected at a time to
operate as a multi-point atrial cathode electrode.
[0106] Certain non-tissue piercing electrodes 722 selected for
atrial pacing and/or atrial sensing may be selected based on atrial
capture threshold tests, electrode impedance, P-wave signal
strength in the cardiac electrical signal, or other factors. For
example, a single one or any combination of two or more individual
non-tissue piercing electrodes 722 functioning as a cathode
electrode that provides an optimal combination of a low pacing
capture threshold amplitude and relatively high electrode impedance
may be selected to achieve reliable atrial pacing using minimal
current drain from the power source 98.
[0107] In some instances, the distal-facing surface 738 may
uniformly contact the atrial endocardial surface when the
tissue-piercing electrode assembly 712 anchors the housing 730 at
the implant site. In that case, all the electrodes 722 may be
selected together to form the atrial cathode. Alternatively, every
other one of the electrodes 722 may be selected together to form a
multi-point atrial cathode having a higher electrical impedance
that is still uniformly distributed along the distal-facing surface
738. Alternatively, a subset of one or more electrodes 722 along
one side of the insulative distal member 772 may be selected to
provide pacing at a desired site that achieves the lowest pacing
capture threshold due to the relative location of the electrodes
722 to the atrial tissue being paced.
[0108] In other instances, the distal-facing surface 738 may be
oriented at an angle relative to the adjacent endocardial surface
depending on the positioning and orientation at which the
tissue-piercing electrode assembly 712 enters the cardiac tissue.
In this situation, one or more of the non-tissue piercing
electrodes 722 may be positioned in contact with the adjacent
endocardial tissue closer than other non-tissue piercing electrodes
722, which may be angled away from the endocardial surface. By
providing multiple non-tissue piercing electrodes along the
periphery of the insulative distal member 772, the angle of the
tissue-piercing electrode assembly 712 and the housing distal end
region 732 relative to the cardiac surface, e.g., the right-atrial
endocardial surface, may not be required to be substantially
parallel. Anatomical and positional differences may cause the
distal-facing surface 738 to be angled or oblique to the
endocardial surface, however, multiple non-tissue piercing
electrodes 722 distributed along the periphery of the insulative
distal member 772 increase the likelihood of good contact between
one or more electrodes 722 and the adjacent cardiac tissue to
promote acceptable pacing thresholds and reliable cardiac event
sensing using at least a subset of multiple electrodes 722. Contact
or fixation circumferentially along the entire periphery of the
insulative distal member 772 may not be required.
[0109] The non-tissue piercing electrodes 722 are shown to each
include a first portion 722a extending along the distal-facing
surface 738 and a second portion 722b extending along the
circumferential surface 739. The first portion 722a and the second
portion 722b may be continuous, exposed surfaces such that the
active electrode surface wraps around a peripheral edge 776 of the
insulative distal member 772 that joins the distal facing surface
738 and the circumferential surface 739. The non-tissue piercing
electrodes 722 may include one or more of the electrodes 722 along
the distal-facing surface 738, one or more electrodes along the
circumferential surface 739, one or more electrodes each extending
along both of the distal-facing surface 738 and the circumferential
surface 739, or any combination thereof. The exposed surface of
each of the non-tissue piercing electrodes 722 may be flush with
respective distal-facing surfaces 738 and/or circumferential
surfaces. In other examples, each of the non-tissue piercing
electrodes 722 may have a raised surface that protrudes from the
insulative distal member 772. Any raised surface of the electrodes
722, however, may define a smooth or rounded, non-tissue piercing
surface.
[0110] The distal fixation and electrode assembly 736 may seal the
distal end region of the housing 730 and may provide a foundation
on which the electrodes 722 are mounted. The electrodes 722 may be
referred to as housing-based electrodes. The electrodes 722 may not
be carried by a shaft or other extension that extends the active
electrode portion away from the housing 730, like the distal tip
electrode 742 residing at the distal tip of the helical shaft 740
extending away from the housing 730. Other examples of non-tissue
piercing electrodes presented herein that are coupled to a
distal-facing surface and/or a circumferential surface of an
insulative distal member include the distal housing-based ring
electrode 22 (FIG. 7), the distal housing-based ring electrode
extending circumferentially around the assembly 36 (FIG. 7), button
electrodes, other housing-based electrodes, and other
circumferential ring electrodes. Any non-tissue piercing electrodes
directly coupled to a distal insulative member, peripherally to a
central tissue-piercing electrode, may be provided to function
individually, collectively, or in any combination as a cathode
electrode for delivering pacing pulses to adjacent cardiac tissue.
When a ring electrode, such as the distal ring electrode 22 and/or
a circumferential ring electrode, is provided, portions of the ring
electrode may be electrically insulated by a coating to provide
multiple distributed non-tissue piercing electrodes along the
distal-facing surface and/or the circumferential surface of the
insulative distal member.
[0111] The non-tissue piercing electrodes 722 and other examples
listed above are expected to provide more reliable and effective
atrial pacing and sensing than a tissue-piercing electrode provided
along the distal fixation and electrode assembly 736. The atrial
chamber walls are relatively thin compared to ventricular chamber
walls. A tissue-piercing atrial cathode electrode may extend too
deep within the atrial tissue leading to inadvertent sustained or
intermittent capture of ventricular tissue. A tissue-piercing
atrial cathode electrode may lead to interference with sensing
atrial signals due to ventricular signals having a larger signal
strength in the cardiac electrical signal received via
tissue-piercing atrial cathode electrodes that are closer in
physical proximity to the ventricular tissue. The tissue-piercing
electrode assembly 712 may be securely anchored into ventricular
tissue for stabilizing the implant position of the device 710 and
providing reasonable certainty that the tip electrode 742 is
sensing and pacing in ventricular tissue while the non-tissue
piercing electrodes 722 are reliably pacing and sensing in the
atrium. When the device 710 is implanted in the target implant
region 4, e.g., as shown in FIG. 1 the ventricular septum, the tip
electrode 742 may reach left ventricular tissue for pacing of the
left ventricle while the non-tissue piercing electrodes 722 provide
pacing and sensing in the right atrium. The tissue-piercing
electrode assembly 712 may be in the range of about 4 to about 8 mm
in length from the distal-facing surface 738 to reach left
ventricular tissue. In some instances, the device 710 may achieve
four-chamber pacing by delivering atrial pacing pulses from the
atrial pacing circuit 83 via the non-tissue piercing electrodes 722
in the target implant region 4 to achieve bi-atrial (right and left
atrial) capture and by delivering ventricular pacing pulses from
the ventricular pacing circuit 85 via the tip electrode 742
advanced into ventricular tissue from the target implant region 4
to achieve biventricular (right and left ventricular) capture.
[0112] FIG. 10 shows an illustrative method 600 of detecting atrial
activity, for example, using the acoustic or motion detector 11 of
FIG. 5, which may be used to represent physiological response
information. In particular, method 600 may include detecting an
atrial contraction based on analysis of a motion signal (e.g.,
provided by the motion detector 11) that may be performed by an IMD
implanted in the patient's heart. In some embodiments, the motion
signal may be provided by an IMD implanted within a ventricle, such
as the right ventricle, of the patient's heart. The method 600 may
include beginning an atrial contraction detection delay period upon
identification of a ventricular activation event 630. The method
600 may include beginning an atrial contraction detection window
upon expiration of the atrial contraction delay period 632. The
method 600 may include analyzing the motion signal within the
atrial contraction detection window.
[0113] The method 600 may include filtering the motion signal
within the atrial contraction detection window, rectifying the
filtered signal, and generating a derivative signal of the filtered
and rectified motion signal 634 within the atrial contraction
detection window. The method 600 may include determining whether an
amplitude of the derivative signal within the atrial contraction
detection window exceeds a threshold 636. In response to
determining that the amplitude of the derivative signal within the
atrial contraction detection window exceeds the threshold (YES of
636), the method 600 may proceed to detecting atrial contraction
638. Otherwise (NO of 636), the method 600 may return to filtering,
rectifying, and generating a derivative signal 634. Various
techniques for using a motion detector that provides a motion
signal may be described in U.S. Pat. No. 9,399,140 (Cho et al.),
issued Jul. 26, 2016, entitled "Atrial contraction detection by a
ventricular leadless pacing device for atrio-synchronous
ventricular pacing," which is incorporated herein by reference in
its entirety.
[0114] As will be described with respect to FIG. 11, heart sounds
(HS) may be detected and used to represent physiological response
information. described herein, the amplitudes and/or relative time
intervals of one or more of the S1 through S4 heart sounds can be
useful in optimizing a patient's hemodynamic response to CRT or
other cardiac therapies that include cardiac pacing and/or neural
stimulation for achieving hemodynamic benefit. The first heart
sound, S1, corresponds to the start of ventricular systole.
Ventricular systole begins when an action potential conducts
through the atrioventricular node (AV node) and quickly depolarizes
the ventricular myocardium. This event is distinguished by the QRS
complex on the ECG. As the ventricles contract, the pressure in the
ventricles begins to rise, causing abrupt closure of the mitral and
tricuspid valves between the ventricles and atria as ventricular
pressure exceeds atrial pressure. This valve closure may generate
S1. S1 generally has a duration of about 150 ms and a frequency on
the order of about 20 to 250 Hz. The amplitude of S1 may provide a
surrogate measurement of LV contractility. Thus, an increase in S1
amplitude positively may correlate with an improvement in LV
contractility. Other measures, like the pre-ejection period
measured from the onset of QRS to S1, may also be used as a
surrogate of myocardial contractility index. Separation of the
closure of the mitral and tricuspid valves due to ventricular
dyssynchrony can be observed as separate M1 and T1 peaks in the S1
signal. Merging of the M1 (mitral valve closure sound) and the T1
(tricuspid valve closure sound) can be used as an indication of
improved ventricular synchrony.
[0115] Generally, left ventricular pressure (LVP) rises
dramatically following the QRS complex of the ECG and closure of
the mitral valve and continues to build during ventricular systole
until the aortic and pulmonary valves open, ejecting blood into the
aorta and pulmonary artery. Ventricular contraction typically
continues to cause blood pressure to rise in the ventricles and the
aorta and pulmonary artery during the ejection phase. As the
contraction diminishes, blood pressure decreases until the aortic
and pulmonary valves close.
[0116] The second heart sound, S2, may be generated by the closure
of the aortic and pulmonary valves, near the end of ventricular
systole and start of ventricular diastole. S2 may, therefore, be
correlated to diastolic pressure in the aorta and the pulmonary
artery. S2 generally has a duration of about 120 ms and a frequency
on the order of 25 to 350 Hz. The time interval between S1 and S2,
i.e., S1-S2 time interval may represent the systolic time interval
(STI) corresponding to the ventricular isovolumic contraction
(pre-ejection) and ejection phase of the cardiac cycle. This S1-S2
time interval may provide a surrogate measurement for stroke
volume. Furthermore, the ratio of the pre-ejection period (Q-S1) to
S1-S2 time may be used as an index of myocardial contractility.
[0117] The third heart sound, S3, is associated with early, passive
diastolic filling of the ventricles, and the fourth heart sound,
S4, may be associated with late, active filling of the ventricles
due to atrial contraction. The third sound is generally difficult
to hear in a normal patient using a stethoscope, and the fourth
sound is generally not heard in a normal patient. Presence of the
third and fourth heart sounds during an examination using a
stethoscope may indicate a pathological condition. The S3 and S4
heart sounds may be used in optimizing pace parameters as they
relate to the diastolic function of the heart. Generally, these
sounds would be minimized or disappear when an optimal pace
parameter is identified. Other aspects of the S1 through S4 heart
sounds and timing thereof that may be useful in cardiac
pace-parameter optimization as known to one having ordinary skill
in the art.
[0118] FIG. 11 is a flowchart 800 of a method for using heart
sounds to optimize pace control parameters according to one
embodiment. Methods of the present disclosure may include one or
more blocks shown in flowchart 800. Other examples of using heart
sounds to optimize cardiac therapy are described generally in U.S.
Pat. No. 9,643,0134, granted May 9, 2017, entitled "System and
method for pacing parameter optimization using heart sounds," which
is incorporated herein by reference in its entirety.
[0119] A pace-parameter optimization method may be initiated at
block 802. The optimization process may be initiated in response to
a user command received via an external programmer. At a time of
initial IMD implantation or during office follow-up visits, or
during a remote patient monitoring session, a user may initiate an
HS-base optimization procedure using an external programmer or
networked computer. Additionally, or alternatively, the process
shown by flowchart 800 may be an automated process started
periodically or in response to sensing a need for therapy delivery
or therapy adjustment based on a sensed physiological signal, which
may include sensed HS signals.
[0120] At block 804 a pace control parameter to be optimized is
selected. A control parameter may be a timing-related parameter,
such as an AV interval or VV interval. Pacing vector is another
control parameter that may be selected at block 804 for
optimization. For example, when a multi-polar lead is used, such as
a coronary sinus lead, multiple bipolar or unipolar pacing vectors
may be selected for pacing in a given heart chamber. The pacing
site associated with a particular pacing vector may have a
significant effect on the hemodynamic benefit of pacing therapy. As
such, pacing vector is one pace control parameter that may be
optimized using methods described herein.
[0121] A pacing sequence is initiated at block 806 using an initial
parameter setting for the test parameter selected at block 804. In
one embodiment, the AV interval is being optimized, and ventricular
pacing is delivered at an initial AV interval setting. It is
understood that an initial AV interval setting may be selected at
block 806 by first measuring an intrinsic AV interval in a patient
having intact AV conduction, i.e., no AV block. An initial AV
interval may be a default pacing interval, the last programmed AV
interval, or a minimum or maximum AV interval to be tested.
Alternatively, if the VV interval is selected for optimization, an
intrinsic inter-ventricular conduction time may be measured first
and paced VV intervals may be iteratively adjusted beginning at a
VV interval longer, shorter, or approximately equal to the
intrinsic VV conduction time.
[0122] An iterative process for adjusting the selected test
parameter to at least two different settings is performed. The
parameter may be adjusted to different settings in any desired
order, e.g., increasing, decreasing, random, etc. For example,
during adjustment of AV interval, an initial AV interval may be set
to just longer than or approximately equal to a measured intrinsic
AV conduction time then iteratively decreased down to a minimum AV
interval test setting. During pacing using each pace parameter
setting, HS signals are acquired at block 808. The iterative
process advances to the next test parameter setting at block 812
until all test parameter settings have been applied, as determined
at block 810, and HS signals have been recorded for each
setting.
[0123] HS signals may be acquired for multiple cardiac cycles to
enable ensemble averaging or averaging of HS parameter measurements
taken from individual cardiac cycles. It is understood that
amplification, filtering, rectification, noise cancellation
techniques or other signal processing steps may be used for
improving the signal-to-noise ratio of the HS signals and these
steps may be different for each of the heart sounds being acquired,
which may include any or all types of heart sounds.
[0124] At least one HS parameter measurement is determined from the
recorded HS signals for each test parameter setting at block 814.
The IMD processor or an external processor, e.g., included in a
programmer, or a combination of both may perform the HS signal
analysis described herein. In one embodiment, S1 and S2 are
recorded and HS parameters are measured using the S1 and S2 signals
at block 814. For example, the amplitude of S1, the V-S2 interval
(where the V event may be a V pace or a sensed R-wave), and the
S1-S2 interval are measured. The presence of S3 and/or S4 may
additionally be noted, or measurements of these signals may be made
for determining related parameters. HS signal parameters are
determined for at least two different test parameter settings,
e.g., at least two different AV intervals, two or more different VV
intervals, or two or more different pacing vectors.
[0125] At block 818, a trend for each HS parameter determined at
block 810 as a function of the pace parameter test settings is
determined. In one embodiment, a trend for each of the V-S2
interval, S1 amplitude, and S1-S2 interval is determined. Other
embodiments may include determining separation of the M1 and T1
sounds during the S1 signal. Based on the trends of the HS
parameter(s) with respect to the varied pace control parameter, an
optimal pace parameter setting may be identified automatically by
the processor at block 820. Additionally, or alternatively, the HS
trends are reported and displayed at block 822 on an external
device such as a programmer or at a remote networked computer.
[0126] If the pace parameter being tested is, for example, pacing
site or pacing vector when a multipolar electrode is positioned
along a heart chamber, such as a quadripolar lead along LV, a
pacing site or vector may be selected based on maximizing an
HS-based surrogate for ventricular contractility. In one
embodiment, the amplitude of S1 is used as a surrogate for
ventricular contractility, and a pacing site or vector associated
with a maximum S1 is identified at block 820 as the optimal pacing
vector setting.
[0127] Determining the trend of each HS parameter at block 818 may
include determining whether the V-S2 interval trend presents a
sudden slope change, e.g., from a substantially flat trend to a
decreasing trend. An AV interval associated with a sudden change in
the V-S2 interval trend may be identified as an optimal AV interval
setting. The optimal AV interval may be further identified based on
other HS trends, for example, a maximum S1 amplitude and/or a
maximum S1-S2 interval.
[0128] In some embodiments, an automatically-identified optimal
pace parameter setting may also be automatically programmed in the
IMD at block 824. In other embodiments, the clinician or user
reviews the reported HS data and recommended pace parameter
setting(s) and may accept a recommended setting or select another
setting based on the HS data.
[0129] HS sensing module, or circuitry, may be operably coupled to
the control circuit 80 (FIG. 8) and be configured to receive analog
signals from an HS sensor for sensing one or more of these heart
sounds. For example, the HS sensing module may include one or more
"channels" configured to particularly sense a specific heart sound
based on frequency, duration, and timing of the heart sounds. For
example, ECG/EGM sensing circuitry may be used by the control
circuit 80 to set HS sensing windows used by HS sensing module for
sensing the heart sounds. HS sensing module may include one or more
sense amplifiers, filters, and rectifiers for optimizing a signal
to noise ratio of heart sound signals. Separate and unique
amplification and filtering properties may be provided for sensing
each of the S1 through S4 sounds to improve signal quality as
needed.
[0130] Bioimpedance, or intracardiac impedance, may be measured and
used to represent physiological response information. For example,
any of the IMDs described herein may measure an intracardiac
impedance signal by injecting a current and measuring a voltage
between electrodes of an electrode vector configuration (e.g.,
selected electrodes). For example, the IMD may measure an impedance
signal by injecting a current (e.g., a non-pacing threshold
current) between a first electrode (e.g., RV electrode) and an
electrode located in the RV proximate the tricuspid valve and
measuring a voltage between the first and second electrodes.
Another vector that may be used is from the LV electrode to the RV
electrode. One will recognize that other vector pair configurations
may be used for stimulation and measurement. Impedance can be
measured between any set of electrodes that encompass the tissue or
cardiac chamber of interest. Thus, one can inject current and
measure voltage to calculate the impedance on the same two
electrodes (a bipolar configuration) or inject current and measure
the voltage on two separate pairs of electrodes (e.g., one pair for
current injection and one pair for voltage sense), hence, a
quadripolar configuration. For a quadripolar electrode
configuration, the current injection and voltage sense electrodes
may be in line with each other (or closely parallel to) and the
voltage sense electrodes may be within the current sense field. For
example, if one injected current between the SVC coil electrode and
the RV tip electrode, voltage sensing may be between the RV coil
electrode and RV ring electrode. In such embodiments, a VfA lead
may be used for the LV cardiac therapy or sensing. The impedance
vectors can be configured to encompass a particular anatomical area
of interest, such as the atrium or ventricles.
[0131] The illustrative methods and/or devices described herein may
monitor one or more electrode vector configurations. Further,
multiple impedance vectors may be measured concurrently and/or
periodically relative to another. In at least one embodiment, the
illustrative methods and/or devices may use impedance waveforms to
acquire selection data (e.g., to find applicable fiducial points,
to allow extraction of measurements from such waveforms, etc.) for
optimizing CRT.
[0132] As used herein, the term "impedance signal" is not limited
to a raw impedance signal. It should be implied that raw impedance
signals may be processed, normalized, and/or filtered (e.g., to
remove artifacts, noise, static, electromagnetic interference
(EMI), and/or extraneous signals) to provide the impedance signal.
Further, the term "impedance signal" may include various
mathematical derivatives thereof including real and imaginary
portions of the impedance signal, a conductance signal based on the
impedance (i.e., the reciprocal or inverse of impedance), etc. In
other words, the term "impedance signal" may be understood to
include conductance signals, i.e., signals that are the reciprocal
of the impedance signal.
[0133] In one or more embodiments of the methods and/or devices
described herein, various patient physiological parameters (e.g.,
intracardiac impedance, heart sounds, cardiac cycle intervals such
as R-R interval, etc.) may be monitored for use in acquiring
selection data to optimize CRT (e.g., set AV and/or VV delay,
optimize cardiac contractility, for example, by using and/or
measuring impedance first derivative dZ/dt, select pacing site,
select pacing vector, lead placement, or assess pacing capture from
both the electrical and mechanical points of view (e.g., electrical
capture may not mean mechanical capture, and the heart sounds and
impedance may assist in assessing whether the electrical stimulus
captures the heart or not by looking at the mechanical information
from the heart sounds and impedance), select an effective electrode
vector configuration for pacing, etc.). For example, intracardiac
impedance signals between two or more electrodes may be monitored
for use in providing such optimization.
[0134] FIG. 12 shows one example of a method 850 for acquiring
selection data for one of the device parameter options (e.g., one
of the selectable device parameters that may be used to optimize
CRT, such as a potential AV delay that may be an optimal
parameter). Other examples of using heart sounds to optimize
cardiac therapy are described generally in U.S. Pat. No. 9,707,399,
granted Jul. 18, 2017, entitled "Cardiac resynchronization therapy
optimization based on intracardiac impedance and heart sounds,"
which is incorporated herein by reference in its entirety.
[0135] As shown, pacing therapy is delivered using one of the
plurality of device options (block 852) (e.g., the plurality of
device parameter options may be selected, determined and/or
calculated AV delays, such as percentages of intrinsic AV delay,
for example, 40% of intrinsic AV delay, 50% of intrinsic AV delay,
60% of intrinsic AV delay, 70% of intrinsic AV delay, 80% of
intrinsic AV delay, etc.). For the device parameter option used to
pace (block 852), selection data is acquired at each of a plurality
of electrode vector configurations (e.g., intracardiac impedance is
monitored over a plurality of cardiac cycles, and selection data is
extracted using such impedance signal). As indicated by the
decision block 854, if selection data has not been acquired from
all desired electrode vector configurations, then the loop of
acquiring selection data (e.g., the loop illustrated by blocks 858,
860, 862, and 864) is repeated. If selection data has been acquired
from all desired electrode vector configurations, then another
different device parameter option is used to deliver therapy (block
856) and the method 850 of FIG. 12 is repeated (e.g., for the
different device parameter option) until selection data has been
acquired for all the different device parameter options (e.g.,
selection data being collected at each of a plurality of electrode
vector configurations for each of the different device parameter
options).
[0136] As shown in the repeated loop of acquiring selection data
for each of the desired electrode vector configurations (e.g.,
blocks 858, 860, 862, and 864), one of the plurality of electrode
vector configurations is selected for use in acquiring selection
data (block 858). Temporal fiducial points associated with at least
a part of a systolic portion of at least one cardiac cycle and/or
temporal fiducial points associated with at least a part of a
diastolic portion of at least one cardiac cycle for the selected
electrode vector configuration are acquired (block 860) (e.g., such
as with use of heart sounds, analysis of impedance signal minimum
and maximums, application of algorithms based on physiological
parameters such as R-R intervals, etc.). For example, temporal
fiducial points associated with the systolic and/or diastolic
portions of the cardiac cycle may be acquired, temporal fiducial
points associated with one or more defined segments within systolic
and/or diastolic portions of the cardiac cycle may be acquired,
and/or temporal fiducial points within or associated with one or
more points and/or portions of a systolic and/or diastolic portion
of the cardiac cycle may be acquired. Yet further, for example,
temporal fiducial points associated with just the systolic portion
or just the diastolic portion of the cardiac cycle may be acquired,
temporal fiducial points associated with one or more defined
segments within just the systolic portion or just the diastolic
portion of the cardiac cycle may be acquired, and/or temporal
fiducial points within or associated with one or more points and/or
portions of just the systolic portion or just the diastolic portion
of the cardiac cycle may be acquired. In other words, fiducial
points may be acquired that are associated with either both the
systolic and diastolic portions of the cardiac cycle or associated
with just one of such portions of the cardiac cycle. Further, for
example, such fiducial points may be representative or indicative
of a measurement window and/or time period (e.g., interval, point,
etc.) at or during which intracardiac impedance may be measured for
use in an analysis as described herein.
[0137] In about the same timeframe (e.g., about simultaneously with
the acquired fiducial points), an intracardiac impedance signal is
acquired at the selected electrode vector configuration (block
862). With the acquired fiducial points and the acquired
intracardiac impedance signal, measurements from the impedance
signal are extracted based on the temporal fiducial points (block
864) (e.g., integral of the impedance signal in a measurement
window defined between fiducial points, maximum slope of impedance
signal in a measurement window defined between fiducial points,
time between the fiducial points, maximum impedance at a fiducial
point, etc.). One or more of such measurements may be comparable to
desired values for such measurements allowing for a determination
of whether the measurement may indicate that the device parameter
option may be an effective device parameter for optimizing therapy
(e.g., a scoring algorithm may be used to determine if a device
parameter option may be an optimal parameter based on whether a
plurality of such measurements meet certain criteria or
thresholds).
[0138] The measurement data for each of the device parameter
options (e.g., obtained such as described in FIG. 12) is determined
for at least one cardiac cycle. In one or more embodiments, such
measurement data is acquired for a plurality of cardiac cycles. The
cardiac cycles during which measurement data is acquired may be any
suitable cardiac cycle. In one or more embodiments, the selected
cardiac cycles during which measurement data is acquired is based
on the respiratory cycle. In at least one embodiment, the
measurement data is acquired during cardiac cycles occurring at the
end of a respiratory cycle (e.g., proximate the end of
expiration).
[0139] FIG. 13 depicts an illustrative system 100 including
electrode apparatus 110, display apparatus 130, and computing
apparatus 140. The electrode apparatus 110 as shown includes a
plurality of electrodes incorporated, or included, within a band
wrapped around the chest, or torso, of a patient 120. The electrode
apparatus 110 is operatively coupled to the computing apparatus 140
(e.g., through one or wired electrical connections, wirelessly,
etc.) to provide electrical signals from each of the electrodes to
the computing apparatus 140 for analysis, evaluation, etc.
Illustrative electrode apparatus may be described in U.S. Pat. No.
9,320,446 entitled "Bioelectric Sensor Device and Methods" and
issued on Apr. 26, 2016, which is incorporated herein by reference
in its entirety. Further, illustrative electrode apparatus 110 will
be described in more detail in reference to FIGS. 14-15.
[0140] Although not described herein, the illustrative system 100
may further include imaging apparatus. The imaging apparatus may be
any type of imaging apparatus configured to image, or provide
images of, at least a portion of the patient in a noninvasive
manner. For example, the imaging apparatus may not use any
components or parts that may be located within the patient to
provide images of the patient except noninvasive tools such as
contrast solution. It is to be understood that the illustrative
systems, methods, and interfaces described herein may further use
imaging apparatus to provide noninvasive assistance to a user
(e.g., a physician) to calibrate and/or deliver a VfA pacing
therapy, to locate and position a device to deliver VfA cardiac
pacing therapy, and/or to locate or select a pacing electrode or
pacing vector proximate the patient's heart for ventricle from
atrium pacing therapy in conjunction with the evaluation of
ventricle from atrium pacing therapy.
[0141] For example, the illustrative systems, methods, and
interfaces may provide image-guided navigation that may be used to
navigate leads including leadless devices, electrodes, leadless
electrodes, wireless electrodes, catheters, etc., within the
patient's body while also providing noninvasive cardiac therapy
evaluation including determining whether a ventricle from atrium
(VfA) paced setting is optimal or determining whether one or more
selected parameters are optimal, such as selected location
information (e.g., location information for the electrodes to
target a particular location in the left ventricle). Illustrative
systems and methods that use imaging apparatus and/or electrode
apparatus may be described in U.S. Patent Publication No.
2014/0371832 filed on Jun. 12, 2013, and entitled "Implantable
Electrode Location Selection," U.S. Patent Publication No.
2014/0371833 filed on Jun. 12, 2013, and entitled "Implantable
Electrode Location Selection," U.S. Patent Publication No.
2014/0323892 filed on Mar. 27, 2014 and entitled "Systems, Methods,
and Interfaces for Identifying Effective Electrodes," U.S. Patent
Publication No. 2014/0323882 filed on Mar. 27, 2014 and entitled
"Systems, Methods, and Interfaces for Identifying
Optical-Electrical Vectors," each of which is incorporated herein
by reference in its entirety.
[0142] Illustrative imaging apparatus may be configured to capture
x-ray images and/or any other alternative imaging modality. For
example, the imaging apparatus may be configured to capture images,
or image data, using isocentric fluoroscopy, bi-plane fluoroscopy,
ultrasound, computed tomography (CT), multi-slice computed
tomography (MSCT), magnetic resonance imaging (MRI), high frequency
ultrasound (HIFU), optical coherence tomography (OCT),
intravascular ultrasound (IVUS), two-dimensional (2D) ultrasound,
three dimensional (3D) ultrasound, four-dimensional (4D)
ultrasound, intraoperative CT, intraoperative MRI, etc. Further, it
is to be understood that the imaging apparatus may be configured to
capture a plurality of consecutive images (e.g., continuously) to
provide video frame data. In other words, a plurality of images
taken over time using the imaging apparatus may provide video
frame, or motion picture, data. Additionally, the images may also
be obtained and displayed in two, three, or four dimensions. In
more advanced forms, four-dimensional surface rendering of the
heart or other regions of the body may also be achieved by
incorporating heart data or other soft tissue data from a map or
from pre-operative image data captured by MRI, CT, or
echocardiography modalities. Image datasets from hybrid modalities,
such as positron emission tomography (PET) combined with CT, or
single photon emission computer tomography (SPECT) combined with
CT, could also provide functional image data superimposed onto
anatomical data, e.g., to be used to navigate treatment apparatus
proximate target locations (e.g., such as locations within the left
ventricle, including a selected location within the high posterior
basal and/or septal area of the left ventricular cavity) within the
heart or other areas of interest.
[0143] Systems and/or imaging apparatus that may be used in
conjunction with the illustrative systems and method described
herein are described in U.S. Pat. App. Pub. No. 2005/0008210 to
Evron et al. published on Jan. 13, 2005, U.S. Pat. App. Pub. No.
2006/0074285 to Zarkh et al. published on Apr. 6, 2006, U.S. Pat.
App. Pub. No. 2011/0112398 to Zarkh et al. published on May 12,
2011, U.S. Pat. App. Pub. No. 2013/0116739 to Brada et al.
published on May 9, 2013, U.S. Pat. No. 6,980,675 to Evron et al.
issued on Dec. 27, 2005, U.S. Pat. No. 7,286,866 to Okerlund et al.
issued on Oct. 23, 2007, U.S. Pat. No. 7,308,297 to Reddy et al.
issued on Dec. 11, 2011, U.S. Pat. No. 7,308,299 to Burrell et al.
issued on Dec. 11, 2011, U.S. Pat. No. 7,321,677 to Evron et al.
issued on Jan. 22, 2008, U.S. Pat. No. 7,346,381 to Okerlund et al.
issued on Mar. 18, 2008, U.S. Pat. No. 7,454,248 to Burrell et al.
issued on Nov. 18, 2008, U.S. Pat. No. 7,499,743 to Vass et al.
issued on Mar. 3, 2009, U.S. Pat. No. 7,565,190 to Okerlund et al.
issued on Jul. 21, 2009, U.S. Pat. No. 7,587,074 to Zarkh et al.
issued on Sep. 8, 2009, U.S. Pat. No. 7,599,730 to Hunter et al.
issued on Oct. 6, 2009, U.S. Pat. No. 7,613,500 to Vass et al.
issued on Nov. 3, 2009, U.S. Pat. No. 7,742,629 to Zarkh et al.
issued on Jun. 22, 2010, U.S. Pat. No. 7,747,047 to Okerlund et al.
issued on Jun. 29, 2010, U.S. Pat. No. 7,778,685 to Evron et al.
issued on Aug. 17, 2010, U.S. Pat. No. 7,778,686 to Vass et al.
issued on Aug. 17, 2010, U.S. Pat. No. 7,813,785 to Okerlund et al.
issued on Oct. 12, 2010, U.S. Pat. No. 7,996,063 to Vass et al.
issued on Aug. 9, 2011, U.S. Pat. No. 8,060,185 to Hunter et al.
issued on Nov. 15, 2011, and U.S. Pat. No. 8,401,616 to Verard et
al. issued on Mar. 19, 2013, each of which is incorporated herein
by reference in its entirety.
[0144] The display apparatus 130 and the computing apparatus 140
may be configured to display and analyze data such as, e.g.,
electrical signals (e.g., electrocardiogram data), cardiac
information representative of one or more of mechanical cardiac
functionality and electrical cardiac functionality (e.g.,
mechanical cardiac functionality only, electrical cardiac
functionality only, or both mechanical cardiac functionality and
electrical cardiac functionality), etc. Cardiac information may
include, e.g., electrical heterogeneity information or electrical
dyssynchrony information, surrogate electrical activation
information or data, etc. that is generated using electrical
signals gathered, monitored, or collected, using the electrode
apparatus 110. In at least one embodiment, the computing apparatus
140 may be a server, a personal computer, or a tablet computer. The
computing apparatus 140 may be configured to receive input from
input apparatus 142 and transmit output to the display apparatus
130. Further, the computing apparatus 140 may include data storage
that may allow for access to processing programs or routines and/or
one or more other types of data, e.g., for calibrating and/or
delivering pacing therapy for driving a graphical user interface
configured to noninvasively assist a user in targeting placement of
a pacing device, and/or for evaluating pacing therapy at that
location (e.g., the location of an implantable electrode used for
pacing, the location of pacing therapy delivered by a particular
pacing vector, etc.).
[0145] The computing apparatus 140 may be operatively coupled to
the input apparatus 142 and the display apparatus 130 to, e.g.,
transmit data to and from each of the input apparatus 142 and the
display apparatus 130. For example, the computing apparatus 140 may
be electrically coupled to each of the input apparatus 142 and the
display apparatus 130 using, e.g., analog electrical connections,
digital electrical connections, wireless connections, bus-based
connections, network-based connections, internet-based connections,
etc. As described further herein, a user may provide input to the
input apparatus 142 to manipulate, or modify, one or more graphical
depictions displayed on the display apparatus 130 and to view
and/or select one or more pieces of information related to the
cardiac therapy.
[0146] Although as depicted the input apparatus 142 is a keyboard,
it is to be understood that the input apparatus 142 may include any
apparatus capable of providing input to the computing apparatus 140
for performing the functionality, methods, and/or logic described
herein. For example, the input apparatus 142 may include a mouse, a
trackball, a touchscreen (e.g., capacitive touchscreen, a resistive
touchscreen, a multi-touch touchscreen, etc.), etc. Likewise, the
display apparatus 130 may include any apparatus capable of
displaying information to a user, such as a graphical user
interface 132 including cardiac information, textual instructions,
graphical depictions of electrical activation information,
graphical depictions of anatomy of a human heart, images or
graphical depictions of the patient's heart, graphical depictions
of a leadless pacing device used to calibrate and/or deliver pacing
therapy, graphical depictions of a leadless pacing device being
positioned or placed to provide VfA pacing therapy, graphical
depictions of locations of one or more electrodes, graphical
depictions of a human torso, images or graphical depictions of the
patient's torso, graphical depictions or actual images of implanted
electrodes and/or leads, etc. Further, the display apparatus 130
may include a liquid crystal display, an organic light-emitting
diode screen, a touchscreen, a cathode ray tube display, etc.
[0147] The processing programs or routines stored and/or executed
by the computing apparatus 140 may include programs or routines for
computational mathematics, matrix mathematics, dispersion
determinations (e.g., standard deviations, variances, ranges,
interquartile ranges, mean absolute differences, average absolute
deviations, etc.), filtering algorithms, maximum value
determinations, minimum value determinations, threshold
determinations, moving windowing algorithms, decomposition
algorithms, compression algorithms (e.g., data compression
algorithms), calibration algorithms, image construction algorithms,
signal processing algorithms (e.g., various filtering algorithms,
Fourier transforms, fast Fourier transforms, etc.), standardization
algorithms, comparison algorithms, vector mathematics, or any other
processing required to implement one or more illustrative methods
and/or processes described herein. Data stored and/or used by the
computing apparatus 140 may include, for example, electrical
signal/waveform data from the electrode apparatus 110, dispersions
signals, windowed dispersions signals, parts or portions of various
signals, electrical activation times from the electrode apparatus
110, graphics (e.g., graphical elements, icons, buttons, windows,
dialogs, pull-down menus, graphic areas, graphic regions, 3D
graphics, etc.), graphical user interfaces, results from one or
more processing programs or routines employed according to the
disclosure herein (e.g., electrical signals, cardiac information,
etc.), or any other data that may be necessary for carrying out the
one and/or more processes or methods described herein.
[0148] In one or more embodiments, the illustrative systems,
methods, and interfaces may be implemented using one or more
computer programs executed on programmable computers, such as
computers that include, for example, processing capabilities, data
storage (e.g., volatile or non-volatile memory and/or storage
elements), input devices, and output devices. Program code and/or
logic described herein may be applied to input data to perform the
functionality described herein and generate desired output
information. The output information may be applied as input to one
or more other devices and/or methods as described herein or as
would be applied in a known fashion.
[0149] The one or more programs used to implement the systems,
methods, and/or interfaces described herein may be provided using
any programmable language, e.g., a high-level procedural and/or
object orientated programming language that is suitable for
communicating with a computer system. Any such programs may, for
example, be stored on any suitable device, e.g., a storage media,
that is readable by a general or special purpose program running on
a computer system (e.g., including processing apparatus) for
configuring and operating the computer system when the suitable
device is read for performing the procedures described herein. In
other words, at least in one embodiment, the illustrative systems,
methods, and/or interfaces may be implemented using a computer
readable storage medium, configured with a computer program, where
the storage medium so configured causes the computer to operate in
a specific and predefined manner to perform functions described
herein. Further, in at least one embodiment, the illustrative
systems, methods, and/or interfaces may be described as being
implemented by logic (e.g., object code) encoded in one or more
non-transitory media that includes code for execution and, when
executed by a processor, is operable to perform operations such as
the methods, processes, and/or functionality described herein.
[0150] The computing apparatus 140 may be, for example, any fixed
or mobile computer system (e.g., a controller, a microcontroller, a
personal computer, minicomputer, tablet computer, etc.) and may be
generally described as including processing circuitry. The exact
configuration of the computing apparatus 140 is not limiting, and
essentially any device capable of providing suitable computing
capabilities and control capabilities (e.g., graphics processing,
etc.) may be used. As described herein, a digital file may be any
medium (e.g., volatile or non-volatile memory, a CD-ROM, a punch
card, magnetic recordable medium such as a disk or tape, etc.)
containing digital bits (e.g., encoded in binary, trinary, etc.)
that may be readable and/or writeable by computing apparatus 140
described herein. Also, as described herein, a file in
user-readable format may be any representation of data (e.g., ASCII
text, binary numbers, hexadecimal numbers, decimal numbers,
graphically, etc.) presentable on any medium (e.g., paper, a
display, etc.) readable and/or understandable by a user.
[0151] In view of the above, it will be readily apparent that the
functionality as described in one or more embodiments according to
the present disclosure may be implemented in any manner as would be
known to one skilled in the art. As such, the computer language,
the computer system, or any other software/hardware which is to be
used to implement the processes described herein shall not be
limiting on the scope of the systems, processes, or programs (e.g.,
the functionality provided by such systems, processes, or programs)
described herein.
[0152] Electrical activation times of the patient's heart may be
useful to evaluate a patient's cardiac condition and/or to
calibrate, deliver, or evaluate ventricle from atrium (VfA) cardiac
therapy to be or being delivered to a patient. Surrogate electrical
activation information or data of one or more regions of a
patient's heart may be monitored, or determined, using electrode
apparatus 110 as shown in FIGS. 13-15. The illustrative electrode
apparatus 110 may be configured to measure body-surface potentials
of a patient 120 and, more particularly, torso-surface potentials
of a patient 120.
[0153] As shown in FIG. 14, the illustrative electrode apparatus
110 may include a set, or array, of electrodes 112, a strap 113,
and interface/amplifier circuitry 116. In at least one embodiment,
a portion of the set of electrodes may be used wherein the portion
corresponds to a particular location on the patient's heart. The
electrodes 112 may be attached, or coupled, to the strap 113, and
the strap 113 may be configured to be wrapped around the torso of a
patient 120 such that the electrodes 112 surround the patient's
heart. As further illustrated, the electrodes 112 may be positioned
around the circumference of a patient 120, including the posterior,
lateral, posterolateral, anterolateral, and anterior locations of
the torso of a patient 120.
[0154] Further, the electrodes 112 may be electrically connected to
interface/amplifier circuitry 116 via wired connection 118. The
interface/amplifier circuitry 116 may be configured to amplify the
signals from the electrodes 112 and provide the signals to the
computing apparatus 140. Other illustrative systems may use a
wireless connection to transmit the signals sensed by electrodes
112 to the interface/amplifier circuitry 116 and, in turn, the
computing apparatus 140, e.g., as channels of data. For example,
the interface/amplifier circuitry 116 may be electrically coupled
to each of the computing apparatus 140 and the display apparatus
130 using, e.g., analog electrical connections, digital electrical
connections, wireless connections, bus-based connections,
network-based connections, internet-based connections, etc.
[0155] Although in the example of FIG. 14 the electrode apparatus
110 includes a strap 113, in other examples any of a variety of
mechanisms, e.g., tape or adhesives, may be employed to aid in the
spacing and placement of electrodes 112. In some examples, the
strap 113 may include an elastic band, strip of tape, or cloth. In
other examples, the electrodes 112 may be placed individually on
the torso of a patient 120. Further, in other examples, electrodes
112 (e.g., arranged in an array) may be part of, or located within,
patches, vests, and/or other manners of securing the electrodes 112
to the torso of the patient 120.
[0156] The electrodes 112 may be configured to surround the heart
of the patient 120 and record, or monitor, the electrical signals
associated with the depolarization and repolarization of the heart
after the signals have propagated through the torso of a patient
120. Each of the electrodes 112 may be used in a unipolar
configuration to sense the torso-surface potentials that reflect
the cardiac signals. The interface/amplifier circuitry 116 may also
be coupled to a return or indifferent electrode (not shown) that
may be used in combination with each electrode 112 for unipolar
sensing. In some examples, there may be about 12 to about 50
electrodes 112 spatially distributed around the torso of the
patient. Other configurations may have more or fewer electrodes
112.
[0157] The computing apparatus 140 may record and analyze the
electrical activity (e.g., torso-surface potential signals) sensed
by electrodes 112 and amplified/conditioned by the
interface/amplifier circuitry 116. The computing apparatus 140 may
be configured to analyze the signals from the electrodes 112 to
provide as anterior and posterior electrode signals and surrogate
cardiac electrical activation times, e.g., representative of
actual, or local, electrical activation times of one or more
regions of the patient's heart as will be further described herein.
The computing apparatus 140 may be configured to analyze the
signals from the electrodes 112 to provide as anterior-septal
electrode signals and surrogate cardiac electrical activation
times, e.g., representative of actual, or local, electrical
activation times of one or more anterior-septal regions of the
patient's heart, as will be further described herein, e.g., for use
in calibrating, delivering, and/or evaluating VfA pacing therapy.
Further, the electrical signals measured at the left anterior
surface location of a patient's torso may be representative, or
surrogates, of electrical signals of the left anterior left
ventricle region of the patient's heart, electrical signals
measured at the left lateral surface location of a patient's torso
may be representative, or surrogates, of electrical signals of the
left lateral left ventricle region of the patient's heart,
electrical signals measured at the left posterolateral surface
location of a patient's torso may be representative, or surrogates,
of electrical signals of the posterolateral left ventricle region
of the patient's heart, and electrical signals measured at the
posterior surface location of a patient's torso may be
representative, or surrogates, of electrical signals of the
posterior left ventricle region of the patient's heart. In one or
more embodiments, measurement of activation times can be performed
by measuring the period of time between an onset of cardiac
depolarization (e.g., onset of QRS complex) and an appropriate
fiducial point such as, e.g., a peak value, a minimum value, a
minimum slope, a maximum slope, a zero crossing, a threshold
crossing, etc.
[0158] Additionally, the computing apparatus 140 may be configured
to provide graphical user interfaces depicting the surrogate
electrical activation times obtained using the electrode apparatus
110. Illustrative systems, methods, and/or interfaces may
noninvasively use the electrical information collected using the
electrode apparatus 110 to evaluate a patient's cardiac condition
and/or to calibrate, deliver, or evaluate VfA pacing therapy to be
or being delivered to the patient.
[0159] FIG. 15 illustrates another illustrative electrode apparatus
110 that includes a plurality of electrodes 112 configured to
surround the heart of the patient 120 and record, or monitor, the
electrical signals associated with the depolarization and
repolarization of the heart after the signals have propagated
through the torso of the patient 120. The electrode apparatus 110
may include a vest 114 upon which the plurality of electrodes 112
may be attached, or to which the electrodes 112 may be coupled. In
at least one embodiment, the plurality, or array, of electrodes 112
may be used to collect electrical information such as, e.g.,
surrogate electrical activation times.
[0160] Similar to the electrode apparatus 110 of FIG. 14, the
electrode apparatus 110 of FIG. 13 may include interface/amplifier
circuitry 116 electrically coupled to each of the electrodes 112
through a wired connection 118 and be configured to transmit
signals from the electrodes 112 to computing apparatus 140. As
illustrated, the electrodes 112 may be distributed over the torso
of a patient 120, including, for example, the anterior, lateral,
posterolateral, anterolateral, and posterior surfaces of the torso
of the patient 120.
[0161] The vest 114 may be formed of fabric with the electrodes 112
attached to the fabric. The vest 114 may be configured to maintain
the position and spacing of electrodes 112 on the torso of the
patient 120. Further, the vest 114 may be marked to assist in
determining the location of the electrodes 112 on the surface of
the torso of the patient 120. In one or more embodiments, the vest
114 may include about 17 or more anterior electrodes positionable
proximate the anterior torso of the patient, and about 39 or more
posterior electrodes positionable proximate the anterior torso of
the patient. In some examples, there may be about 25 electrodes 112
to about 256 electrodes 112 distributed around the torso of the
patient 120, though other configurations may have more or fewer
electrodes 112.
[0162] As described herein, the electrode apparatus 110 may be
configured to measure electrical information (e.g., electrical
signals) representing different regions of a patient's heart. For
example, activation times of different regions of a patient's heart
can be approximated from surface electrocardiogram (ECG) activation
times measured using surface electrodes in proximity to surface
areas corresponding to the different regions of the patient's
heart. In at least one example, activation times of the
anterior-septal region of a patient's heart can be approximated
from surface ECG activation times measured using surface electrodes
in proximity to surface areas corresponding to the anterior-septal
region of the patient's heart. That is, a portion of the set of
electrodes 112, and not the entire set, can be used to generate
activation times corresponding to a particular location of the
patient's heart that the portion of the set of electrodes
corresponds to.
[0163] The illustrative systems, methods, and interfaces may be
used to provide noninvasive assistance to a user in the evaluation
of a patient's cardiac health or status, and/or the evaluation of
cardiac therapy such as ventricle from atrium (VfA) pacing therapy
by use of the electrode apparatus 110 (e.g., cardiac therapy being
presently-delivered to a patient during implantation or after
implantation). Further, the illustrative systems, methods, and
interfaces may be used to assist a user in the configuration, or
calibration, of the cardiac therapy, such as VfA pacing therapy, to
be or being delivered to a patient.
[0164] VfA pacing can be described as providing a synchronized
homogeneous activation of ventricles of the heart. As an example,
patients with atrial-ventricular (AV) block or prolonged AV timings
that can lead to heart failure who have otherwise intact (e.g.,
normal) QRS can benefit from VfA pacing therapy. In addition, as an
example, VfA pacing may provide beneficial activation for heart
failure patients with intrinsic ventricular conduction disorders.
Further, proper placement of VfA pacing can provide optimal
activation of the ventricles for such patients. Further, left
ventricular (LV) resynchronization for heart failure patients with
left bundle branch block (LBBB) may find that VfA pacing enables
easier access to left ventricular endocardium without exposing the
leadless device or lead to the endocardial blood pool. At the same
time, in that example, this can help engage part of the conduction
system to potentially correct LBBB and effectively resynchronize
the patient.
[0165] Electrical activity may be monitored using a plurality of
external electrodes, such as electrodes 112 of FIGS. 13-15. The
electrical activity can be monitored by a plurality of electrodes
during VfA pacing therapy or in the absence of VfA pacing therapy.
The monitored electrical activity can be used to evaluate VfA
pacing therapy to a patient. The electrical activity monitored
using the ECG belt described can be used to evaluate at least one
paced setting of the VfA pacing therapy on the heart. As an
example, a paced setting can be any one parameter or a combination
of parameters including, but not limited to, electrode position,
pacing polarity, pacing output, pacing pulse width, timing at which
VfA pacing is delivered relative to atrial (A) timing, pacing rate,
etc. Further, as an example, the location of the leadless device or
a pacing lead can include a location in the left ventricle,
accessed through the right atrium within, or in close proximity to,
the high posterior basal and/or septal (HPBS) area of the left
ventricular cavity. Moreover, pacing in, or in close proximity to,
the HPBS area can be selective (e.g., involving stimulation of a
particular area of the HPBS alone) or non-selective (e.g., combined
pacing at the location of the HPBS and other atrial and/or
ventricular septum areas).
[0166] Further, body-surface isochronal maps of ventricular
activation can be constructed using the monitored electrical
activity during VfA pacing therapy or in the absence of VfA pacing
therapy. The monitored electrical activity and/or the map of
ventricular activation can be used to generate electrical
heterogeneity information (EHI). The electrical heterogeneity
information can include determining metrics of electrical
heterogeneity. The metrics of electrical heterogeneity can include
a metric of standard deviation of activation times (SDAT) of
electrodes on a left side of a torso of the patient and/or a metric
of mean left ventricular activation time (LVAT) of electrodes on
the left side of the torso of the patient. A metric of LVAT may be
determined from electrodes on both the anterior and posterior
surfaces, which are more proximal to the left ventricle. The
metrics of electrical heterogeneity information can include a
metric of mean right ventricular activation time (RVAT) of
electrodes on the right side of the torso of the patient. A metric
of RVAT may be determined from electrodes on both the anterior and
posterior surfaces which are more proximal to the right ventricle.
The metrics of electrical heterogeneity can include a metric of
mean total activation time (mTAT) taken from a plurality of
electrode signals from both sides of the torso of the patient, or
it may include other metrics (e.g., standard deviation,
interquartile deviations, a difference between a latest activation
time and earliest activation time) reflecting a range or dispersion
of activation times on a plurality of electrodes located on the
right side of the patient torso or left side of the patient torso,
or combining both right and left sides of the patient torso. The
metrics of electrical heterogeneity information can include a
metric of anterior-septal activation times (ASAT) of electrodes on
the torso in close proximity to the anterior-septal portion of the
heart.
[0167] Electrical heterogeneity information (EHI) may be generated
during delivery of VfA pacing therapy at one or more VfA paced
settings. The electrical heterogeneity information can be generated
using metrics of electrical heterogeneity. As an example, the
metrics of electrical heterogeneity can include one or more of an
SDAT, an LVAT, an RVAT, an mTAT, and an ASAT. In at least one
embodiment, only ASAT may be determined and further used, and/or
ASAT may be more heavily weighted than other values.
[0168] One or more paced settings associated with the VfA pacing
therapy may be evaluated. A paced setting can include a plurality
of pacing parameters. The plurality of pacing parameters can be
optimal if the patient's cardiac condition improves, if the VfA
pacing therapy is effectively capturing a desired portion of the
left ventricle (e.g., the high posterior basal and/or septal area),
and/or if a metric of electrical heterogeneity improves by a
certain threshold compared to a baseline rhythm or therapy. In at
least one embodiment, the determination of whether the paced
setting is optimal can be based on at least one metric of
electrical heterogeneity generated from electrical activity during
VfA pacing (and also, in some embodiments, during native
conduction, or in the absence of VfA pacing). The at least one
metric can include one or more of an SDAT, an LVAT, an RVAT, an
mTAT, and an ASAT.
[0169] Further, the plurality of pacing parameters can be optimal
if a metric of electrical heterogeneity is greater than or less
than a particular threshold, and/or if the location of the pacing
therapy to excite the left ventricle causes a particular pattern of
excitation of the muscle fibers in the heart. In addition, the
plurality of pacing parameters can be optimal if a metric of
electrical heterogeneity indicates a correction of a left bundle
branch block (LBBB), and/or if a metric of electrical heterogeneity
indicates a complete engagement of a Purkinje system, etc. As an
example, a metric of electrical heterogeneity of an ASAT less than
or equal to a threshold (e.g., a threshold of 30 ms) and an LVAT
less than or equal to a threshold (e.g., a threshold of 30 ms) can
indicate a correction of an LBBB, and thus, the paced setting is
optimal. As an example, a metric of electrical heterogeneity of an
RVAT less than or equal to a threshold (e.g., a threshold of 30
ms), an ASAT less than or equal to a threshold (e.g., a threshold
of 30 ms), and an LVAT less than or equal to a threshold (e.g., a
threshold of 30 ms) can indicate a complete engagement of the
Purkinje system, and thus the paced setting is may be optimal.
[0170] The paced setting can be determined to be optimal in
response to the VfA pacing therapy using the paced setting being
acceptable, being beneficial, being indicative of complete
engagement of patient's native cardiac conduction system, being
indicative of correction of a ventricular conduction disorder
(e.g., left bundle branch block), etc. A paced setting can include
one or more of a pacing electrode position (including one or more
of a depth, an angle, an amount of turn for a screw-based fixation
mechanism, etc.), a voltage, a pulse width, an intensity, a pacing
polarity, a pacing vector, a pacing waveform, a timing of the
pacing delivered relative to an intrinsic or paced atrial event or
relative to the intrinsic His bundle potential, and/or a pacing
location, etc. A pacing vector can include any two or more pacing
electrodes such as, e.g., a tip electrode to a can electrode, a tip
electrode to a ring electrode etc., that are used to deliver the
VfA pacing therapy, etc. The pacing location can refer to the
location of any of the one or more pacing electrodes that are
positioned using a lead, a leadless device, and/or any device or
apparatus configured to deliver VfA.
[0171] A paced setting for VfA pacing therapy may be adjusted. In
at least one embodiment, the paced setting can be adjusted in
response to the paced setting being not optimal. In at least one
embodiment, the paced setting can be adjusted in response to the
paced setting being within an optimal range but in order to
determine whether the paced setting can be at a position within the
optimal range that is more beneficial, more useful, more
functional, etc., for the VfA pacing therapy. The paced setting
could be adjusted to find the most optimal metric of electrical
heterogeneity.
[0172] In one or more embodiments, a determination of whether the
paced setting is optimal can be based on a particular metric of
electrical heterogeneity using an ECG belt. In at least one
example, the paced setting can be adjusted at intervals that
correlate with a change in the metric of electrical heterogeneity
until the metric of electrical heterogeneity is at or proximate a
particular metric value. For instance, the adjusting of the paced
setting can cause the metric of electrical heterogeneity to
approach a particular threshold metric of electrical heterogeneity
and, as the metric approaches the particular threshold, the rate at
which the paced setting is adjusted can be slowed down. Put another
way, as the metric of electrical heterogeneity is further from the
particular threshold metric, the paced setting can be adjusted more
quickly and as the metric of electrical heterogeneity gets closer
to the particular threshold metric, the paced setting can be
adjusted more slowly until the metric of electrical heterogeneity
is at the particular threshold metric.
[0173] Various techniques for utilizing an electrode apparatus
having a plurality of external electrodes to monitor electrical
activity from tissue of a patient that may be used with the
devices, systems, and methods described herein are disclosed in
U.S. patent application Ser. No. 15/934,517, filed 23 Mar. 2018,
entitled "Evaluation of Ventricle from Atrium Pacing Therapy,"
which is incorporated herein by reference in its entirety.
[0174] Locating an implantation site that is adjacent to or within
the triangle of Koch region may be facilitated using various
delivery systems and techniques of the present disclosure. Various
delivery systems and techniques may be used to deliver a pacing
lead including a tissue-piercing electrode to the implantation site
adjacent to or within the triangle of Koch region. In particular,
some delivery systems and techniques may be used to deliver a
pacing lead to a target implantation zone in the coronary sinus
(e.g., near the coronary sinus ostium) that is adjacent to the
triangle of Koch region.
[0175] In some embodiments, pacing leads of the present disclosure
that are delivered to the implantation site may have the same or
similar structure and features as the leads shown in FIGS. 1-4. A
pacing lead may include an elongate body defining a lumen extending
from a proximal portion to a distal portion.
[0176] A left-ventricular (LV) electrode may be coupled to the
elongate body, which is implantable from tissue adjacent to or
within the triangle of Koch region of the right atrium (RA) through
the right-atrial endocardium and central fibrous body. The LV
electrode may be configured to deliver cardiac therapy to or sense
electrical activity of the left ventricle in the basal and/or
septal region of the left ventricular myocardium of a patient's
heart. The LV electrode may be configured to pierce tissue in an
implantation site adjacent to or within the triangle of Koch region
of the right atrium of the patient's heart to secure the pacing
lead to the implantation site.
[0177] A right-atrial (RA) electrode may also be coupled to the
elongate body of the pacing lead proximal to the LV electrode and
positionable within the RA. The RA electrode may be configured to
deliver cardiac therapy to or sense electrical activity of the
right atrium of the patient's heart.
[0178] FIGS. 16-25 show various configurations of a pacing lead
delivery system 500. FIG. 16 shows a pacing lead delivery system
500 that may be used to deliver a pacing lead to an implantation
site adjacent to or within the triangle of Koch region. As
illustrated, the delivery system 500 may include a sheath 502
extending from a proximal portion 504 (e.g., proximal end portion)
to a distal portion 506 (e.g., distal end portion). The sheath 502
may include an elongate body defining a lumen extending between the
proximal portion 504 and the distal portion 506. The lumen of the
sheath 502 may be configured to receive a guide wire. The lumen may
be configured to receive guide wires of one or more sizes (e.g.,
one or more diameters).
[0179] The sheath 502 of the delivery system 500 may be
deflectable, have a fixed curve, or be any combination of these. A
deflectable sheath may be formed of any flexible or semi-rigid
material that is suitable for use during implantation (e.g.,
biocompatible). A fixed curve sheath may be formed of any rigid or
semi-rigid material that is suitable for use during implantation
(e.g., biocompatible) such that one or more curve segments may be
described as substantially fixed or unchanging.
[0180] The sheath 502 may define or include one, two, three, or
more curve segments. In some embodiments, the sheath 502 has two or
more curves or curve segments. In the illustrated embodiment, the
sheath 502 of the delivery system 500 has a first curve segment 532
and a second curve segment 534. The first curve segment 532 may be
used to reach the coronary sinus ostium or the triangle of Koch
region from outside the patient's heart. The second curve segment
534 may be used to point, or orient, the distal portion 506 of the
sheath 502 towards the membranous septum (e.g., septal wall)
adjacent to the LV. For example, the second curve segment 534 may
be used to point the distal end of the sheath 502 towards the
triangle of Koch region or a region just inside the coronary sinus
near the coronary sinus ostium (e.g., adjacent to the triangle of
Koch region). In some embodiments, the first curve segment 532 may
have a fixed curve, and the second curve segment 534 may have a
fixed curve, which may telescope relative to the first curve
segment.
[0181] The curve segments may be deflectable, fixed, or a
combination of both. For example, the first curve segment 532 may
have a fixed curve, and the second curve segment 534 may be
deflectable. In some embodiments, a deflectable curve segment may
be configured to telescope. For example, the first curve segment
532 (e.g., an outer sheath or catheter) may be a separate piece
from the second curve segment 534 (e.g., an inner sheath or
catheter), and the second curve segment may be configured to
telescope, or be adjusted, within a lumen of the first curve
segment 532. In some embodiments, the second curve segment 534 may
be configured to be adjustable by rotating relative to the first
curve segment 532, for example, up to 360 degrees.
[0182] The curve segments may have the same or different
curvatures. For example, in some embodiments, the first curve
segment 532 may define a first radius of curvature and the second
curve segment 534 may define a second radius of curvature, which
may be less than the first radius of curvature. In some
embodiments, the first curve segment 532 may be aligned to a first
plane, and the second curve segment 534 may be aligned to a second
plane having a different orientation than the first plane. For
example, the first plane may be orthogonal to the second plane. In
some embodiments, the first curve segment 532 may be adjustable
relative to the second curve segment 534 (e.g., rotatable or
telescoping). In general, the curvatures of the sheath 502 may be
defined based on the target implantation site.
[0183] Various other components of the pacing lead delivery system
500 may be the same or similar to aspects described in U.S. Pat.
No. 6,132,456, issued Oct. 17, 2000, entitled "Arrangement for
implanting an endocardial cardiac lead," which is incorporated
herein by reference in its entirety.
[0184] FIG. 17 shows a close up view of the distal portion 506 of
the sheath 502 and the second curve segment 534 of the sheath. As
illustrated, a needle-tipped dilator 508 extends, or protrudes,
distally from the distal portion 506 of the sheath 502. The
needle-tipped dilator 508 may extend at least partially through the
lumen of the sheath 502. The needle-tipped dilator 508 may be
configured to form an opening in tissue in a potential implantation
site. In some embodiments, the needle-tipped dilator 508, or a
portion of the needle-tipped dilator 508, may be electrically
conductive (e.g., active). The needle-tipped dilator 508 may be
used to engage tissue at a potential implantation site and may
monitor or deliver electrical stimulation to a potential
implantation site, which may facilitate determining whether the
potential implantation site is acceptable.
[0185] FIGS. 18A-C show various configurations near the distal
portion 506 of the sheath 502. FIG. 18A shows the needle-tipped
dilator 508 extending distally out of the sheath 502. The
needle-tipped dilator 508 may be configured to be received within
the lumen of the sheath 502. A guide wire 510 may also be received
within the lumen of the sheath 502 and optionally within a lumen of
the needle-tipped dilator 508.
[0186] The needle-tipped dilator 508 may include a needle portion
512 and a dilator portion 514. In some embodiments, the
needle-tipped dilator 508 may be formed of a single integral piece.
In other embodiments, the needle portion 512 and the dilator
portion 514 may be separately formed pieces that cooperatively
function as a needle-tipped dilator. For example, the needle
portion 512 may be received within a lumen of the dilator portion
514 and separable, or freely translatable, in a longitudinal
direction (e.g., aligned to the length of the sheath when
received). In some embodiments, the needle portion 512, the dilator
portion 514, or both may be electrically conductive (e.g., active)
or insulating (e.g., passive).
[0187] The needle-tipped dilator 508 may define, or include, a
lumen extending from a proximal portion to a distal portion of the
needle-tipped dilator. In some embodiments, the lumen of the
needle-tipped dilator 508 may be configured to be advanced over a
guide wire 510 or a guide wire 511. As illustrated, the diameter of
guide wire 511 may be greater than the diameter of guide wire
510.
[0188] FIGS. 18B-C show a pacing lead 516 extending distally out of
the sheath 502. The pacing lead 516 may be freely translatable in a
longitudinal direction relative to the sheath 502, the guide wire
510, or both. At least the pacing lead 516 may be freely rotatable
relative to the sheath 502, the guide wire 510, or both. In
general, the pacing lead 516 may be guided by the guidewire 510 as
shown in FIG. 18B to the implantation site, the lumen of the sheath
502 as shown in FIG. 18C, or both.
[0189] The pacing lead 516 may include an elongate body extending
from a proximal portion to a distal portion. As illustrated, the
pacing lead 516 may also include a fixation element 518 coupled to
the distal portion of the pacing lead. The fixation element 518 may
be configured to be attached to an implantation site in the
right-atrial endocardium adjacent to or within the triangle of Koch
region in the right atrium of a patient's heart. Any suitable
fixation structure may be used for the fixation element 518. In the
illustrated embodiment, the fixation element 518 is a helical
attachment element.
[0190] In some embodiments, the fixation element 518 may also
function as the LV electrode (e.g., tissue-piercing electrode
having a helical shape). In other embodiments, the fixation element
518 may be separately formed from the LV electrode (e.g., if the LV
electrode is a dart-type electrode). For example, the fixation
element 518 may be disposed proximal to the LV electrode along the
pacing lead 516.
[0191] Although not shown here, the pacing lead 516 may include an
atrial electrode, such as a right-atrial (RA) electrode, a
left-atrial (LA) electrode, or both. The RA electrode may be
positioned adjacent to, or some distance proximal to, the fixation
element 518, the LV electrode, or both. The RA electrode may be
positioned on the pacing lead 516 such that the RA electrode is
positioned adjacent in the RA when the LV electrode is implanted.
The LA electrode may be positioned adjacent to, or some distance
proximal to, the fixation element 518, the LV electrode, or both.
The LA electrode may be positioned on the pacing lead 516 such that
the LA electrode is positioned adjacent to the proximal part of the
coronary sinus when the LV electrode is implanted. The RA
electrode, the LA electrode, or both may be used to sense or pace
the respective portions of the atrium of the patient's heart. In
some embodiments, the RA electrode, LA electrode, or both may be
used to provide timing and coordination information about atrial
activity.
[0192] As shown in FIG. 18B, the pacing lead 516 may include a
lumen extending through the elongate body. The lumen of the pacing
lead 516 may be configured to receive the guide wire 510. In some
embodiments, the lumen of the pacing lead 516 may not be able to
accommodate the size, or diameter, of the guide wire 511, which may
influence the implantation method selected.
[0193] FIG. 19 shows the distal portion 506 of the sheath 502 with
the guide wire 511 received in and extending out of the lumen of
the needle-tipped dilator 508. As shown, the needle-tipped dilator
508 received in and extending out of the lumen of the sheath
502.
[0194] FIG. 20 is an illustration of the distal portion 506 of the
sheath 502 with the guide wire 510 received in and extending out of
a lumen of the sheath 502. As illustrated, the diameter of the
guide wire 511 (FIG. 19) is greater than the diameter of the guide
wire 510.
[0195] FIGS. 21-25 show various configurations using the guide wire
510 (see FIG. 20) that may be used during a delivery procedure.
FIG. 21 shows the distal portion 506 of the sheath 502 including
the needle-tipped dilator 508 and the guide wire 510 in a position
that may be used to advance toward a potential implantation
site.
[0196] FIG. 22 shows the distal portion 506 of the sheath 502 with
the guide wire 510 retracted, or drawn back, into the lumen of the
needle-tipped dilator 508. This position may be used to test the
potential implantation site using the needle portion 512. In some
embodiments, the needle portion 512 may be inserted into the tissue
to test the response to electrical pulses and/or to sense
electrical activity at one or more depths within the tissue. If the
implantation site is acceptable, the dilator portion 514, the guide
wire 510, or both may be pushed further into the tissue to create a
hole in the tissue, which may be used to receive the pacing lead.
The guide wire 510 may be used, for example, when the guide wire is
formed to be semi-rigid or rigid (e.g., stiff) such that the guide
wire can be pushed into the tissue without requiring the
needle-tipped dilator 508 to push into the tissue. In some
embodiments, the guide wire 510 may be used instead of the
needle-tipped dilator 508 for one or more functions described
herein.
[0197] FIG. 23 shows a proximal portion 504 of the sheath 502
including the guide wire 510 and the needle-tipped dilator 508. As
illustrated, the needle-tipped dilator 508 may be removed from
sheath 502 and the guide wire 510 in a proximal direction, for
example, after the potential implantation site is determined to be
acceptable.
[0198] FIG. 24 shows the proximal portion 504 of the sheath 502
including the guide wire 510 and the pacing lead 516. As
illustrated, the needle-tipped dilator 508 (FIG. 23) may be
exchanged for the pacing lead 516. The guide wire 510 may be
described as an exchange wire or an exchange-length wire, which may
have sufficient length to facilitate such exchanges.
[0199] The guide wire 510 may remain at least partially disposed in
the lumen of the sheath 502. In some embodiments, a distal end of
the guide wire 510 may be positioned in a hole in the implantation
site that was formed by the needle-tipped dilator 508. The pacing
lead 516 may be advanced distally over the guide wire 510 toward
the implantation site.
[0200] In another embodiment (not shown), the guide wire 510 may be
removed in a proximal direction from the sheath 502 along with the
needle-tipped dilator 508. The distal portion 506 of the sheath 502
may be positioned in a hole in the implantation site that was
formed by the needle-tipped dilator 508. The pacing lead 516 may be
advanced distally through the lumen of the sheath 502 to the
implantation site.
[0201] FIG. 25 shows the distal portion 506 of the sheath 502 with
the pacing lead 516 extending distally out of the lumen of the
sheath and the guide wire 510 extending distally out of the lumen
of the pacing lead. This position may be used to advance the pacing
lead 516 to the implantation site.
[0202] Once the pacing lead 516 reaches the implantation site, the
tissue at the site may be tested using the pacing lead (e.g., the
LV electrode of the pacing lead). Testing the implantation site may
include delivering electrical pulses (e.g., stimulation), sensing
or monitoring electrical activity (e.g., intrinsic activity or the
response to electrical pulses), or both. If the implantation site
is acceptable, pacing lead 516 may be fixed to the implantation
site, and the guide wire 510 may be retracted, along with the
sheath 502.
[0203] Various methods may be used with the pacing lead delivery
system 500 described in FIGS. 16-25 to implant the pacing lead
adjacent to or within the triangle of Koch region. FIGS. 26-34 show
various techniques that may be used for delivery.
[0204] FIGS. 26-27 show the pacing lead delivery system 500
advanced to an implantation site. FIG. 26 shows a right anterior
oblique cutaway view of the patient's heart 8. FIG. 27 shows an
overhead cutaway view. In some embodiments, the delivery system 500
may be configured to position the LV electrode of the pacing lead
less than or equal to 3 centimeters (cm), 2 cm, 1 cm, or even 0.5
cm into the coronary sinus from the right atrium. The first curve
segment 532 may be used to position the delivery system 500 near
the triangle of Koch region, and the second curve segment 534 may
be used to orient the distal portion into the implantation site
adjacent to or within the triangle of Koch region. As illustrated,
the implantation site is adjacent to the triangle of Koch region
(e.g., in the coronary sinus 3 near the coronary sinus ostium).
[0205] FIG. 27 shows the pacing lead delivery system 500 relative
to the aortic valve 540, the pulmonary valve 542, the right
coronary artery 544, the tricuspid valve 6, the mitral valve 546,
the coronary sinus 3, and the great coronary vein 548.
[0206] FIG. 28 shows a target implantation zone 550 that is
adjacent to the triangle of Koch region in the coronary sinus near
the coronary sinus ostium. The target implantation zone 550 is
below the mitral valve 546 within the coronary sinus on the LV
wall. The angle of implantation into the target implantation zone
550 may be selected to deliver the LV electrode of the pacing lead
into the basal region, septal region, or basal-septal region of the
left ventricular myocardium.
[0207] FIG. 29 shows a method 900 of using a pacing lead delivery
system of the present disclosure, such as pacing lead delivery
system 500 (FIGS. 16-28). The method 900 may include locating a
potential implantation site 902. In some embodiments, the potential
implantation site may be adjacent to or within the triangle of Koch
region in the right atrium of a patient's heart. The method 900 may
include advancing a pacing lead to the potential implantation site
904. The pacing lead may include an elongate body extending from a
proximal portion to a distal portion and a fixation element coupled
to the distal portion and attachable to the right-atrial
endocardium adjacent to or within the triangle of Koch region in
the right atrium of the patient's heart, for example, to deliver
cardiac therapy to or sense electrical activity of the left
ventricle in the basal region, septal region, or basal-septal
region of the left ventricular myocardium of the patient's
heart.
[0208] The method 900 may include implanting the pacing lead at the
potential implantation site 906. In some embodiments, implanting
the pacing lead may include implanting a left-ventricular electrode
coupled to the distal portion of the pacing lead from tissue
adjacent to or within the triangle of Koch region of the right
atrium through the right-atrial endocardium and optionally the
central fibrous body to deliver cardiac therapy to or sense
electrical activity of the left ventricle in the basal and/or
septal region of the left ventricular myocardium of the patient's
heart. For example, when implanting through the coronary sinus, the
right fibrous trigone and membranous septum may not be penetrated
by the left-ventricular electrode. In some embodiments, the
left-ventricular electrode may be described as being implanted from
tissue adjacent to or within the triangle of Koch region of the
right atrium through the right-atrial endocardium and the central
fibrous skeleton. In some embodiments, implanting the pacing lead
may include positioning a right-atrial electrode of the pacing lead
proximal to the fixation element to deliver cardiac therapy to or
sense electrical activity of the right atrium of the patient's
heart.
[0209] FIG. 30 shows one example of the method for locating a
potential implantation site 902. The method 902 may include
inserting a guide wire into a lumen of a sheath 912. The method 902
may include advancing the guide wire and the sheath to the
implantation site 914, for example, into the coronary sinus of the
patient's heart to a region below the mitral valve near the
coronary sinus ostium.
[0210] The method 902 may include advancing a needle-tipped dilator
916, for example, over the guide wire and through the lumen of the
sheath to the coronary sinus. The method 902 may also include
engaging tissue in the potential implantation site 918, for
example, adjacent to or within the triangle of Koch region in the
right atrium of the patient's heart with the needle-tipped
dilator.
[0211] The method 902 may include testing the potential
implantation site 920 that is adjacent to or within the triangle of
Koch region in the right atrium of the patient's heart using the
needle-tipped dilator. The method 902 may also include determining
whether the potential implantation site is acceptable 922, for
example, based on the testing using the needle-tipped dilator.
[0212] FIG. 31 shows a further example of a method for locating a
potential implantation site 902. The method 902 may include
determining if the site is acceptable 922. In response to the site
being not acceptable, the method 902 may include withdrawing the
needle-tipped dilator 926, for example, from tissue in the
potential implantation site. The method 902 may also include
locating a new potential implantation site 928, for example,
adjacent to or within the triangle of Koch region in the right
atrium of the patient's heart.
[0213] In response to the site being acceptable, the method 902 may
include forming an opening in tissue 930, for example, in the
potential implantation site using the needle-tipped dilator. The
method 902 may also include preparing the implantation site for the
pacing lead, for example, based on the size of the guide wire. For
example, one implantation method 940 (FIG. 32) may be used for a
guide wire having a larger diameter (e.g., 0.035 inches), whereas
another implantation method 950 (FIG. 33) may be used for a guide
wire having a smaller diameter (e.g., 0.014 inches).
[0214] FIG. 32 shows one example of a method for preparing an
implantation site 940. The method 940 may include advancing the
guide wire to the potential implantation site 942. The method 940
may also include advancing a sheath over the guide wire 944, for
example, into an opening in tissue in the potential implantation
site formed by a needle-tipped dilator. In some embodiments, the
sheath may be advanced as far as possible into the opening.
[0215] The method 940 may include withdrawing the needle-tipped
dilator 946, for example, through the lumen of the sheath. The
guide wire may also be withdrawn through the lumen of the sheath.
The method 940 may also include advancing the pacing lead to the
potential implantation site 948, for example, while the pacing lead
is at least partially disposed in the lumen of the sheath such that
the sheath guides the pacing lead to the potential implantation
site.
[0216] FIG. 33 shows another example of a method for preparing an
implantation site 950. The method 950 may include advancing the
guide wire into an opening in tissue in the implantation site 952,
for example, formed by a needle-tipped dilator. The method 950 may
also include withdrawing the needle-tipped dilator 954, for
example, over the guide wire such that the pacing lead is guided to
the implantation site by the guide wire.
[0217] The method 950 may include exchanging the needle-tipped
dilator for the pacing lead 956. The method 950 may also include
advancing the pacing lead 958, for example, over the guide wire to
the implantation site.
[0218] FIG. 34 shows a further example of a method for preparing an
implantation site 960, which may follow the method 940 or the
method 950. The method 960 may include testing the implantation
site using the pacing lead 962, for example, after the pacing lead
has been guided to the implantation site by the sheath or the guide
wire. The method 960 may also include determining whether the
potential implantation site is acceptable 964, for example, based
on the testing using the pacing lead.
[0219] Based on the determination, in response to the implantation
site being not acceptable 966, the method 960 may include locating
a new potential implantation site 968. The method 960 may return to
testing with a needle-tipped dilator or the pacing lead.
[0220] In response to the implantation site being acceptable 966,
the method 960 may include fixing the pacing lead in the
implantation site 970. The sheath or guidewire may be removed after
the pacing lead is implanted and deemed acceptable, and only the
pacing lead may remain at the implantation site. In particular, an
LV electrode may be positioned in the basal region, septal region,
or basal-septal region of the left ventricular myocardium through a
region adjacent to or within the triangle of Koch region.
[0221] In some embodiments, an imageable material (e.g., radiopaque
material) may be used to form part or all of some components of the
delivery system to guide the distal portion of the delivery system
to an implantation site that is adjacent to or within the triangle
of Koch region to position the LV electrode in the basal region,
septal region, or basal-septal region of the left ventricular
myocardium. For example, a distal portion of the sheath may be at
least partially formed of an imageable material. Various examples
of imageable materials and imageable components (e.g., imageable
members) are described in U.S. patent application Ser. No.
16/227,774, filed Dec. 20, 2018, entitled "Implantable medical
device delivery for cardiac therapy," which is incorporated herein
by reference in its entirety.
Illustrative Embodiments
[0222] While the present disclosure is not so limited, an
appreciation of various aspects of the disclosure will be gained
through a discussion of the illustrative embodiments provided
below. Various modifications of the illustrative embodiments, as
well as additional embodiments of the disclosure, will become
apparent herein.
[0223] In illustrative embodiment A1, a method of delivering a
pacing lead comprises locating a potential implantation site
adjacent to or within the triangle of Koch region in the right
atrium of a patient's heart; advancing a pacing lead to the
potential implantation site, the pacing lead comprising an elongate
body extending from a proximal portion to a distal portion and a
fixation element coupled to the distal portion and attachable to
the right-atrial endocardium adjacent to or within the triangle of
Koch region in the right atrium of the patient's heart; and
implanting the pacing lead at the potential implantation site to
deliver cardiac therapy to and sense electrical activity of the
left ventricle in the basal region, septal region, or basal-septal
region of the left ventricular myocardium of the patient's
heart.
[0224] In illustrative embodiment A2, a method comprises a method
according to any A embodiment, further comprising implanting a
left-ventricular electrode coupled to the distal portion of the
pacing lead from tissue adjacent to or within the triangle of Koch
region of the right atrium through the right-atrial endocardium and
optionally the central fibrous body to deliver cardiac therapy to
and sense electrical activity of the left ventricle in the basal
region, septal region, or basal-septal region of the left
ventricular myocardium of the patient's heart.
[0225] In illustrative embodiment A3, a method comprises a method
according to any A embodiment, further comprising positioning an
atrial electrode of the pacing lead adjacent to or proximal to the
fixation element to deliver cardiac therapy to or sense electrical
activity of the atrium of the patient's heart.
[0226] In illustrative embodiment A4, a method comprises a method
according to any A embodiment, wherein locating the potential
implantation site comprises: optionally inserting a guide wire into
a lumen of a sheath; advancing the guide wire and the sheath into
the coronary sinus of the patient's heart; advancing a
needle-tipped dilator over the guide wire and through the lumen of
the sheath to the coronary sinus; engaging tissue in the potential
implantation site adjacent to or within the triangle of Koch region
in the right atrium of the patient's heart with the needle-tipped
dilator; testing the potential implantation site adjacent to or
within the triangle of Koch region in the right atrium of the
patient's heart using the needle-tipped dilator; and determining
whether the potential implantation site is acceptable based on the
testing using the needle-tipped dilator.
[0227] In illustrative embodiment A5, a method comprises a method
according to embodiment A4, further comprising: withdrawing the
needle-tipped dilator from tissue in the potential implantation
site in response to determining that the potential implantation
site is not acceptable; and optionally locating a new potential
implantation site adjacent to or within the triangle of Koch region
in the right atrium of the patient's heart.
[0228] In illustrative embodiment A6, a method comprises a method
according to embodiment A4 or A5, further comprising forming an
opening in tissue in the potential implantation site using the
needle-tipped dilator in response to determining that the potential
implantation site is acceptable.
[0229] In illustrative embodiment A7, a method comprises a method
according to any A embodiment, further comprising preparing the
potential implantation site for the pacing lead based on a size of
a guide wire.
[0230] In illustrative embodiment A8, a method comprises a method
according to embodiment A7, wherein preparing the potential
implantation site for the pacing lead comprises: advancing the
guide wire to the potential implantation site; advancing a sheath
over the guide wire and into an opening in tissue in the potential
implantation site formed by a needle-tipped dilator; and
withdrawing the needle-tipped dilator and the guide wire through a
lumen of the sheath, wherein the pacing lead is advanced to the
potential implantation site while the pacing lead is at least
partially disposed in the lumen of the sheath.
[0231] In illustrative embodiment A9, a method comprises a method
according to embodiment A7, wherein preparing the potential
implantation site for the pacing lead comprises: advancing the
guide wire into an opening in tissue in the potential implantation
site formed by a needle-tipped dilator; withdrawing the
needle-tipped dilator over the guide wire; and exchanging the
needle-tipped dilator with the pacing lead, wherein the pacing lead
is advanced to the potential implantation site over the guide
wire.
[0232] In illustrative embodiment A10, a method comprises a method
according to any embodiment A4-A9, wherein the needle-tipped
dilator comprises a dilator portion and a needle portion separable
from the dilator portion.
[0233] In illustrative embodiment A11, a method comprises a method
according to any A embodiment, further comprising: testing the
potential implantation site using the pacing lead; determining
whether the potential implantation site is acceptable based on the
testing using the pacing lead; and fixing the pacing lead in the
potential implantation site in response to determining that the
potential implantation site is acceptable based on the testing
using the pacing lead.
[0234] In illustrative embodiment B1, a pacing lead delivery system
comprises a sheath comprising an elongate body defining a lumen
extending between a proximal portion and a distal portion; a guide
wire at least partially disposable in the lumen of the sheath; a
needle-tipped dilator configured to advance over the guide wire and
to engage tissue in a potential implantation site; and a pacing
lead comprising an elongate body extending from a proximal portion
to a distal portion and a fixation element coupled to the distal
portion and attachable to an implantation site in the right-atrial
endocardium adjacent to or within the triangle of Koch region in
the right atrium of a patient's heart to deliver cardiac therapy to
and sense electrical activity of the left ventricle in the basal
region, septal region, or basal-septal region of the left
ventricular myocardium of the patient's heart.
[0235] In illustrative embodiment B2, a system comprises a system
of any B embodiment, wherein the elongate body defines a lumen
extending between the proximal portion and the distal portion
configured to receive the guide wire.
[0236] In illustrative embodiment B3, a system comprises a system
of any B embodiment, wherein the fixation element of the pacing
lead comprises a helical attachment element.
[0237] In illustrative embodiment B4, a system comprises a system
of embodiment B3, wherein the pacing lead is freely rotatable
relative to the sheath, the guide wire, or both.
[0238] In illustrative embodiment B5, a system comprises a system
of any B embodiment, wherein the sheath comprises a fixed curve
configured to extend to the implantation site adjacent to or within
the triangle of Koch region in the right atrium of the patient's
heart using the coronary sinus.
[0239] In illustrative embodiment B6, a system comprises a system
of any B embodiment, wherein the sheath is deflectable and
comprises a first curve segment and a second curve segment distal
to the first curve segment configured to extend to the implantation
site adjacent to or within the triangle of Koch region in the right
atrium of the patient's heart through the coronary sinus.
[0240] In illustrative embodiment B7, a system comprises a system
of embodiment B6, wherein the first curve segment has a first
radius of curvature and the second curve segment has a second
radius of curvature less than the first radius of curvature.
[0241] In illustrative embodiment B8, a system comprises a system
of embodiment B6 or B7, wherein the first curve segment is aligned
to a first plane and the second curve segment is aligned to a
second plane having a different orientation than the first
plane.
[0242] In illustrative embodiment B9, a system comprises the system
of any embodiment B6-B8, wherein the first curve segment is
adjustable relative to the second curve segment.
[0243] In illustrative embodiment B10, a system comprises a system
according to any B embodiment, wherein the needle-tipped dilator or
guide wire is configured to form an opening in tissue in the
potential implantation site.
[0244] In illustrative embodiment B11, a system comprises a system
according to embodiment B10, wherein the sheath is configured to be
inserted into the opening in tissue formed by the needle-tipped
dilator to guide the pacing lead to the potential implantation
site.
[0245] In illustrative embodiment B12, a system comprises a system
according to embodiment B10, wherein the guide wire is configured
to be inserted into the opening in tissue formed by the
needle-tipped dilator to guide advancement of the pacing lead to
the potential implantation site.
[0246] In illustrative embodiment C1, a pacing lead comprises an
elongate body defining a lumen extending from a proximal portion to
a distal portion configured to receive a guide wire; and a
left-ventricular electrode coupled to the elongate body implantable
from tissue adjacent to or within the triangle of Koch region of
the right atrium through the right-atrial endocardium to deliver
cardiac therapy to and sense electrical activity of the left
ventricle in the basal region, septal region, or basal-septal
region of the left ventricular myocardium of a patient's heart.
[0247] In illustrative embodiment C2, a pacing lead comprises a
pacing lead according to any C embodiment, further comprising an
atrial electrode coupled to the elongate body proximal to the
left-ventricular electrode and positionable within the atrium to
deliver cardiac therapy to or sense electrical activity of the
atrium of the patient's heart.
[0248] In illustrative embodiment C3, a pacing lead comprises a
pacing lead according to any C embodiment, wherein the
left-ventricular electrode is configured to pierce tissue in an
implantation site adjacent to or within the triangle of Koch region
of the right atrium of the patient's heart to secure the pacing
lead to the left ventricular myocardium.
[0249] In illustrative embodiment C4, a pacing lead comprises a
pacing lead according to any C embodiment, wherein the
left-ventricular electrode comprises a helical attachment
element.
[0250] In illustrative embodiment D1, a pacing lead delivery system
comprises a sheath comprising an elongate body defining a lumen
extending between a proximal portion and a distal portion; a guide
wire at least partially disposable in the lumen of the sheath and
configured to engage tissue in a potential implantation site; and a
pacing lead comprising an elongate body extending from a proximal
portion to a distal portion and a fixation element coupled to the
distal portion and attachable to an implantation site in the
right-atrial endocardium adjacent to or within the triangle of Koch
region in the right atrium of a patient's heart to and sense
electrical activity of the left ventricle in the basal region,
septal region, or basal-septal region of the left ventricular
myocardium of the patient's heart.
[0251] In illustrative embodiment D2, a system comprises a system
according to any D embodiment, wherein the elongate body defines a
lumen extending between the proximal portion and the distal portion
configured to receive the guide wire.
[0252] Thus, various embodiments of DELIVERY SYSTEMS AND METHODS
FOR LEFT VENTRICULAR PACING are disclosed. Although reference is
made herein to the accompanying set of drawings that form part of
this disclosure, one of at least ordinary skill in the art will
appreciate that various adaptations and modifications of the
embodiments described herein are within, or do not depart from, the
scope of this disclosure. For example, aspects of the embodiments
described herein may be combined in a variety of ways with each
other. Therefore, it is to be understood that, within the scope of
the appended claims, the claimed invention may be practiced other
than as explicitly described herein.
[0253] It should be understood that various aspects disclosed
herein may be combined in different combinations than the
combinations specifically presented in the description and
accompanying drawings. It should also be understood that, depending
on the example, certain acts or events of any of the processes or
methods described herein may be performed in a different sequence,
may be added, merged, or left out altogether (e.g., all described
acts or events may not be necessary to carry out the techniques).
In addition, while certain aspects of this disclosure are described
as being performed by a single module or unit for purposes of
clarity, it should be understood that the techniques of this
disclosure may be performed by a combination of units or modules
associated with, for example, a medical device.
[0254] In one or more examples, the described techniques may be
implemented in hardware, software, firmware, or any combination
thereof. If implemented in software, the functions may be stored as
one or more instructions or code on a computer-readable medium and
executed by a hardware-based processing unit. Computer-readable
media may include non-transitory computer-readable media, which
corresponds to a tangible medium such as data storage media (e.g.,
RAM, ROM, EEPROM, flash memory, or any other medium that can be
used to store desired program code in the form of instructions or
data structures and that can be accessed by a computer).
[0255] Instructions may be executed by one or more processors, such
as one or more digital signal processors (DSPs), general purpose
microprocessors, application specific integrated circuits (ASICs),
field programmable logic arrays (FPGAs), or other equivalent
integrated or discrete logic circuitry. Accordingly, the term
"processor" as used herein may refer to any of the foregoing
structure or any other physical structure suitable for
implementation of the described techniques. Also, the techniques
could be fully implemented in one or more circuits or logic
elements. It will be understood that each block of the block
diagrams and combinations of those blocks can be implemented by
means for performing the illustrated function.
[0256] All references and publications cited herein are expressly
incorporated herein by reference in their entirety for all
purposes, except to the extent any aspect directly contradicts this
disclosure.
[0257] All scientific and technical terms used herein have meanings
commonly used in the art unless otherwise specified. The
definitions provided herein are to facilitate understanding of
certain terms used frequently herein and are not meant to limit the
scope of the present disclosure.
[0258] Unless otherwise indicated, all numbers expressing feature
sizes, amounts, and physical properties used in the specification
and claims may be understood as being modified either by the term
"exactly" or "about." Accordingly, unless indicated to the
contrary, the numerical parameters set forth in the foregoing
specification and attached claims are approximations that can vary
depending upon the desired properties sought to be obtained by
those skilled in the art utilizing the teachings disclosed herein
or, for example, within typical ranges of experimental error.
[0259] The recitation of numerical ranges by endpoints includes all
numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2,
2.75, 3, 3.80, 4, and 5) and any range within that range. Herein,
the terms "up to" or "no greater than" a number (e.g., up to 50)
includes the number (e.g., 50), and the term "no less than" a
number (e.g., no less than 5) includes the number (e.g., 5).
[0260] The terms "coupled" or "connected" refer to elements being
attached to each other either directly (in direct contact with each
other) or indirectly (having one or more elements between and
attaching the two elements). Either term may be modified by
"operatively" and "operably," which may be used interchangeably, to
describe that the coupling or connection is configured to allow the
components to interact to carry out at least some
functionality.
[0261] Terms related to orientation, such as "proximal," "distal,"
"above," and "below," are used to describe relative positions of
components and are not meant to limit the orientation of the
embodiments contemplated. For example, an embodiment described as
having a "top" and "bottom" also encompasses embodiments thereof
rotated in various directions unless the content clearly dictates
otherwise.
[0262] Reference to "one embodiment," "an embodiment," "certain
embodiments," or "some embodiments," etc., means that a particular
feature, configuration, composition, or characteristic described in
connection with the embodiment is included in at least one
embodiment of the disclosure. Thus, the appearances of such phrases
in various places throughout are not necessarily referring to the
same embodiment of the disclosure. Furthermore, the particular
features, configurations, compositions, or characteristics may be
combined in any suitable manner in one or more embodiments.
[0263] The words "preferred" and "preferably" refer to embodiments
of the disclosure that may afford certain benefits, under certain
circumstances. However, other embodiments may also be preferred,
under the same or other circumstances. Furthermore, the recitation
of one or more preferred embodiments does not imply that other
embodiments are not useful and is not intended to exclude other
embodiments from the scope of the disclosure.
[0264] As used in this specification and the appended claims, the
singular forms "a," "an," and "the" encompass embodiments having
plural referents, unless the content clearly dictates otherwise. As
used in this specification and the appended claims, the term "or"
is generally employed in its sense including "and/or" unless the
content clearly dictates otherwise.
[0265] As used herein, "have," "having," "include," "including,"
"comprise," "comprising" or the like are used in their open-ended
sense, and generally mean "including, but not limited to." It will
be understood that "consisting essentially of," "consisting of,"
and the like are subsumed in "comprising," and the like.
[0266] The term "and/or" means one or all of the listed elements or
a combination of at least two of the listed elements.
[0267] The phrases "at least one of," "comprises at least one of,"
and "one or more of" followed by a list refers to any one of the
items in the list and any combination of two or more items in the
list.
* * * * *